diff --git a/api/BUILD.gn b/api/BUILD.gn
index b6caeaa..539c222 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -52,6 +52,7 @@
     "candidate.cc",
     "candidate.h",
     "cryptoparams.h",
+    "datachannelinterface.cc",
     "datachannelinterface.h",
     "dtmfsenderinterface.h",
     "jsep.cc",
@@ -68,6 +69,7 @@
     "mediatypes.h",
     "notifier.h",
     "peerconnectionfactoryproxy.h",
+    "peerconnectioninterface.cc",
     "peerconnectioninterface.h",
     "peerconnectionproxy.h",
     "proxy.cc",
@@ -81,6 +83,7 @@
     "rtpreceiverinterface.cc",
     "rtpreceiverinterface.h",
     "rtpsenderinterface.h",
+    "rtptransceiverinterface.cc",
     "rtptransceiverinterface.h",
     "setremotedescriptionobserverinterface.h",
     "statstypes.cc",
@@ -90,11 +93,6 @@
     "videosourceproxy.h",
   ]
 
-  if (!build_with_chromium && is_clang) {
-    # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
-    suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
-  }
-
   deps = [
     ":array_view",
     ":audio_options_api",
diff --git a/api/datachannelinterface.cc b/api/datachannelinterface.cc
new file mode 100644
index 0000000..141462d
--- /dev/null
+++ b/api/datachannelinterface.cc
@@ -0,0 +1,35 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/datachannelinterface.h"
+
+namespace webrtc {
+
+bool DataChannelInterface::ordered() const {
+  return false;
+}
+
+uint16_t DataChannelInterface::maxRetransmitTime() const {
+  return 0;
+}
+
+uint16_t DataChannelInterface::maxRetransmits() const {
+  return 0;
+}
+
+std::string DataChannelInterface::protocol() const {
+  return std::string();
+}
+
+bool DataChannelInterface::negotiated() const {
+  return false;
+}
+
+}  // namespace webrtc
diff --git a/api/datachannelinterface.h b/api/datachannelinterface.h
index 5cbe717..a0d2b3b 100644
--- a/api/datachannelinterface.h
+++ b/api/datachannelinterface.h
@@ -88,7 +88,7 @@
   virtual void OnBufferedAmountChange(uint64_t previous_amount) {}
 
  protected:
-  virtual ~DataChannelObserver() {}
+  virtual ~DataChannelObserver() = default;
 };
 
 class DataChannelInterface : public rtc::RefCountInterface {
@@ -134,11 +134,11 @@
   // TODO(deadbeef): Remove these dummy implementations when all classes have
   // implemented these APIs. They should all just return the values the
   // DataChannel was created with.
-  virtual bool ordered() const { return false; }
-  virtual uint16_t maxRetransmitTime() const { return 0; }
-  virtual uint16_t maxRetransmits() const { return 0; }
-  virtual std::string protocol() const { return std::string(); }
-  virtual bool negotiated() const { return false; }
+  virtual bool ordered() const;
+  virtual uint16_t maxRetransmitTime() const;
+  virtual uint16_t maxRetransmits() const;
+  virtual std::string protocol() const;
+  virtual bool negotiated() const;
 
   // Returns the ID from the DataChannelInit, if it was negotiated out-of-band.
   // If negotiated in-band, this ID will be populated once the DTLS role is
@@ -170,7 +170,7 @@
   virtual bool Send(const DataBuffer& buffer) = 0;
 
  protected:
-  virtual ~DataChannelInterface() {}
+  ~DataChannelInterface() override = default;
 };
 
 }  // namespace webrtc
diff --git a/api/dtmfsenderinterface.h b/api/dtmfsenderinterface.h
index 217f9d2..b79bb31 100644
--- a/api/dtmfsenderinterface.h
+++ b/api/dtmfsenderinterface.h
@@ -29,7 +29,7 @@
   virtual void OnToneChange(const std::string& tone) = 0;
 
  protected:
-  virtual ~DtmfSenderObserverInterface() {}
+  virtual ~DtmfSenderObserverInterface() = default;
 };
 
 // The interface of native implementation of the RTCDTMFSender defined by the
@@ -85,7 +85,7 @@
   virtual int inter_tone_gap() const = 0;
 
  protected:
-  virtual ~DtmfSenderInterface() {}
+  ~DtmfSenderInterface() override = default;
 };
 
 }  // namespace webrtc
diff --git a/api/jsep.cc b/api/jsep.cc
index 1f4afba..52a60f9 100644
--- a/api/jsep.cc
+++ b/api/jsep.cc
@@ -21,4 +21,21 @@
   return 0;
 }
 
+void CreateSessionDescriptionObserver::OnFailure(RTCError error) {
+  OnFailure(error.message());
+}
+
+void CreateSessionDescriptionObserver::OnFailure(const std::string& error) {
+  OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
+}
+
+void SetSessionDescriptionObserver::OnFailure(RTCError error) {
+  std::string message(error.message());
+  OnFailure(message);
+}
+
+void SetSessionDescriptionObserver::OnFailure(const std::string& error) {
+  OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
+}
+
 }  // namespace webrtc
diff --git a/api/jsep.h b/api/jsep.h
index dbf97f6..b07f858 100644
--- a/api/jsep.h
+++ b/api/jsep.h
@@ -205,10 +205,8 @@
   // is deprecated; in order to let clients remove the old version, it has a
   // default implementation. If both versions are unimplemented, the
   // result will be a runtime error (stack overflow). This is intentional.
-  virtual void OnFailure(RTCError error) { OnFailure(error.message()); }
-  virtual void OnFailure(const std::string& error) {
-    OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
-  }
+  virtual void OnFailure(RTCError error);
+  virtual void OnFailure(const std::string& error);
 
  protected:
   ~CreateSessionDescriptionObserver() override = default;
@@ -219,13 +217,9 @@
  public:
   virtual void OnSuccess() = 0;
   // See description in CreateSessionDescriptionObserver for OnFailure.
-  virtual void OnFailure(RTCError error) {
-    std::string message(error.message());
-    OnFailure(message);
-  }
-  virtual void OnFailure(const std::string& error) {
-    OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
-  }
+  virtual void OnFailure(RTCError error);
+
+  virtual void OnFailure(const std::string& error);
 
  protected:
   ~SetSessionDescriptionObserver() override = default;
diff --git a/api/peerconnectioninterface.cc b/api/peerconnectioninterface.cc
new file mode 100644
index 0000000..aa23da3
--- /dev/null
+++ b/api/peerconnectioninterface.cc
@@ -0,0 +1,248 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/peerconnectioninterface.h"
+
+namespace webrtc {
+
+PeerConnectionInterface::IceServer::IceServer() = default;
+PeerConnectionInterface::IceServer::IceServer(const IceServer& rhs) = default;
+PeerConnectionInterface::IceServer::~IceServer() = default;
+
+PeerConnectionInterface::RTCConfiguration::RTCConfiguration() = default;
+
+PeerConnectionInterface::RTCConfiguration::RTCConfiguration(
+    const RTCConfiguration& rhs) = default;
+
+PeerConnectionInterface::RTCConfiguration::RTCConfiguration(
+    RTCConfigurationType type) {
+  if (type == RTCConfigurationType::kAggressive) {
+    // These parameters are also defined in Java and IOS configurations,
+    // so their values may be overwritten by the Java or IOS configuration.
+    bundle_policy = kBundlePolicyMaxBundle;
+    rtcp_mux_policy = kRtcpMuxPolicyRequire;
+    ice_connection_receiving_timeout = kAggressiveIceConnectionReceivingTimeout;
+
+    // These parameters are not defined in Java or IOS configuration,
+    // so their values will not be overwritten.
+    enable_ice_renomination = true;
+    redetermine_role_on_ice_restart = false;
+  }
+}
+
+PeerConnectionInterface::RTCConfiguration::~RTCConfiguration() = default;
+
+RTCErrorOr<rtc::scoped_refptr<RtpSenderInterface>>
+PeerConnectionInterface::AddTrack(
+    rtc::scoped_refptr<MediaStreamTrackInterface> track,
+    const std::vector<std::string>& stream_ids) {
+  return RTCError(RTCErrorType::UNSUPPORTED_OPERATION, "Not implemented");
+}
+
+RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
+PeerConnectionInterface::AddTransceiver(
+    rtc::scoped_refptr<MediaStreamTrackInterface> track) {
+  return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
+}
+
+RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
+PeerConnectionInterface::AddTransceiver(
+    rtc::scoped_refptr<MediaStreamTrackInterface> track,
+    const RtpTransceiverInit& init) {
+  return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
+}
+
+RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
+PeerConnectionInterface::AddTransceiver(cricket::MediaType media_type) {
+  return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
+}
+
+RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
+PeerConnectionInterface::AddTransceiver(cricket::MediaType media_type,
+                                        const RtpTransceiverInit& init) {
+  return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
+}
+
+rtc::scoped_refptr<RtpSenderInterface> PeerConnectionInterface::CreateSender(
+    const std::string& kind,
+    const std::string& stream_id) {
+  return rtc::scoped_refptr<RtpSenderInterface>();
+}
+
+std::vector<rtc::scoped_refptr<RtpSenderInterface>>
+PeerConnectionInterface::GetSenders() const {
+  return std::vector<rtc::scoped_refptr<RtpSenderInterface>>();
+}
+
+std::vector<rtc::scoped_refptr<RtpReceiverInterface>>
+PeerConnectionInterface::GetReceivers() const {
+  return std::vector<rtc::scoped_refptr<RtpReceiverInterface>>();
+}
+
+std::vector<rtc::scoped_refptr<RtpTransceiverInterface>>
+PeerConnectionInterface::GetTransceivers() const {
+  return {};
+}
+
+const SessionDescriptionInterface*
+PeerConnectionInterface::current_local_description() const {
+  return nullptr;
+}
+
+const SessionDescriptionInterface*
+PeerConnectionInterface::current_remote_description() const {
+  return nullptr;
+}
+
+const SessionDescriptionInterface*
+PeerConnectionInterface::pending_local_description() const {
+  return nullptr;
+}
+
+const SessionDescriptionInterface*
+PeerConnectionInterface::pending_remote_description() const {
+  return nullptr;
+}
+
+PeerConnectionInterface::RTCConfiguration
+PeerConnectionInterface::GetConfiguration() {
+  return PeerConnectionInterface::RTCConfiguration();
+}
+
+bool PeerConnectionInterface::SetConfiguration(
+    const PeerConnectionInterface::RTCConfiguration& config,
+    RTCError* error) {
+  return false;
+}
+
+bool PeerConnectionInterface::SetConfiguration(
+    const PeerConnectionInterface::RTCConfiguration& config) {
+  return false;
+}
+
+bool PeerConnectionInterface::RemoveIceCandidates(
+    const std::vector<cricket::Candidate>& candidates) {
+  return false;
+}
+
+RTCError PeerConnectionInterface::SetBitrate(const BitrateSettings& bitrate) {
+  BitrateParameters bitrate_parameters;
+  bitrate_parameters.min_bitrate_bps = bitrate.min_bitrate_bps;
+  bitrate_parameters.current_bitrate_bps = bitrate.start_bitrate_bps;
+  bitrate_parameters.max_bitrate_bps = bitrate.max_bitrate_bps;
+  return SetBitrate(bitrate_parameters);
+}
+
+RTCError PeerConnectionInterface::SetBitrate(
+    const BitrateParameters& bitrate_parameters) {
+  BitrateSettings bitrate;
+  bitrate.min_bitrate_bps = bitrate_parameters.min_bitrate_bps;
+  bitrate.start_bitrate_bps = bitrate_parameters.current_bitrate_bps;
+  bitrate.max_bitrate_bps = bitrate_parameters.max_bitrate_bps;
+  return SetBitrate(bitrate);
+}
+
+bool PeerConnectionInterface::StartRtcEventLog(rtc::PlatformFile file,
+                                               int64_t max_size_bytes) {
+  return false;
+}
+
+bool PeerConnectionInterface::StartRtcEventLog(
+    std::unique_ptr<RtcEventLogOutput> output,
+    int64_t output_period_ms) {
+  return false;
+}
+
+PeerConnectionInterface::BitrateParameters::BitrateParameters() = default;
+
+PeerConnectionInterface::BitrateParameters::~BitrateParameters() = default;
+
+PeerConnectionDependencies::PeerConnectionDependencies(
+    PeerConnectionObserver* observer_in)
+    : observer(observer_in) {}
+
+PeerConnectionDependencies::PeerConnectionDependencies(
+    PeerConnectionDependencies&&) = default;
+
+PeerConnectionDependencies::~PeerConnectionDependencies() = default;
+
+PeerConnectionFactoryDependencies::PeerConnectionFactoryDependencies() =
+    default;
+
+PeerConnectionFactoryDependencies::PeerConnectionFactoryDependencies(
+    PeerConnectionFactoryDependencies&&) = default;
+
+PeerConnectionFactoryDependencies::~PeerConnectionFactoryDependencies() =
+    default;
+
+rtc::scoped_refptr<PeerConnectionInterface>
+PeerConnectionFactoryInterface::CreatePeerConnection(
+    const PeerConnectionInterface::RTCConfiguration& configuration,
+    const MediaConstraintsInterface* constraints,
+    std::unique_ptr<cricket::PortAllocator> allocator,
+    std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator,
+    PeerConnectionObserver* observer) {
+  return nullptr;
+}
+
+rtc::scoped_refptr<PeerConnectionInterface>
+PeerConnectionFactoryInterface::CreatePeerConnection(
+    const PeerConnectionInterface::RTCConfiguration& configuration,
+    std::unique_ptr<cricket::PortAllocator> allocator,
+    std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator,
+    PeerConnectionObserver* observer) {
+  return nullptr;
+}
+
+rtc::scoped_refptr<PeerConnectionInterface>
+PeerConnectionFactoryInterface::CreatePeerConnection(
+    const PeerConnectionInterface::RTCConfiguration& configuration,
+    PeerConnectionDependencies dependencies) {
+  return nullptr;
+}
+
+RtpCapabilities PeerConnectionFactoryInterface::GetRtpSenderCapabilities(
+    cricket::MediaType kind) const {
+  return {};
+}
+
+RtpCapabilities PeerConnectionFactoryInterface::GetRtpReceiverCapabilities(
+    cricket::MediaType kind) const {
+  return {};
+}
+
+rtc::scoped_refptr<VideoTrackSourceInterface>
+PeerConnectionFactoryInterface::CreateVideoSource(
+    std::unique_ptr<cricket::VideoCapturer> capturer) {
+  return nullptr;
+}
+
+rtc::scoped_refptr<VideoTrackSourceInterface>
+PeerConnectionFactoryInterface::CreateVideoSource(
+    std::unique_ptr<cricket::VideoCapturer> capturer,
+    const MediaConstraintsInterface* constraints) {
+  return nullptr;
+}
+
+rtc::scoped_refptr<VideoTrackSourceInterface>
+PeerConnectionFactoryInterface::CreateVideoSource(
+    cricket::VideoCapturer* capturer) {
+  return CreateVideoSource(std::unique_ptr<cricket::VideoCapturer>(capturer));
+}
+
+rtc::scoped_refptr<VideoTrackSourceInterface>
+PeerConnectionFactoryInterface::CreateVideoSource(
+    cricket::VideoCapturer* capturer,
+    const MediaConstraintsInterface* constraints) {
+  return CreateVideoSource(std::unique_ptr<cricket::VideoCapturer>(capturer),
+                           constraints);
+}
+
+}  // namespace webrtc
diff --git a/api/peerconnectioninterface.h b/api/peerconnectioninterface.h
index 90a99a6..786fdef 100644
--- a/api/peerconnectioninterface.h
+++ b/api/peerconnectioninterface.h
@@ -102,6 +102,7 @@
 // TODO(bugs.webrtc.org/7447): We plan to provide a way to let applications
 // inject a PacketSocketFactory and/or NetworkManager, and not expose
 // PortAllocator in the PeerConnection api.
+#include "media/base/mediaengine.h"  // nogncheck
 #include "p2p/base/portallocator.h"  // nogncheck
 // TODO(nisse): The interface for bitrate allocation strategy belongs in api/.
 #include "rtc_base/bitrateallocationstrategy.h"
@@ -119,7 +120,6 @@
 }  // namespace rtc
 
 namespace cricket {
-class MediaEngineInterface;
 class WebRtcVideoDecoderFactory;
 class WebRtcVideoEncoderFactory;
 }  // namespace cricket
@@ -144,7 +144,7 @@
 
  protected:
   // Dtor protected as objects shouldn't be deleted via this interface.
-  ~StreamCollectionInterface() {}
+  ~StreamCollectionInterface() override = default;
 };
 
 class StatsObserver : public rtc::RefCountInterface {
@@ -152,7 +152,7 @@
   virtual void OnComplete(const StatsReports& reports) = 0;
 
  protected:
-  virtual ~StatsObserver() {}
+  ~StatsObserver() override = default;
 };
 
 enum class SdpSemantics { kPlanB, kUnifiedPlan };
@@ -198,6 +198,10 @@
   };
 
   struct IceServer {
+    IceServer();
+    IceServer(const IceServer&);
+    ~IceServer();
+
     // TODO(jbauch): Remove uri when all code using it has switched to urls.
     // List of URIs associated with this server. Valid formats are described
     // in RFC7064 and RFC7065, and more may be added in the future. The "host"
@@ -284,22 +288,10 @@
     // methods for all settings which are of interest to applications,
     // Chrome in particular.
 
-    RTCConfiguration() = default;
-    explicit RTCConfiguration(RTCConfigurationType type) {
-      if (type == RTCConfigurationType::kAggressive) {
-        // These parameters are also defined in Java and IOS configurations,
-        // so their values may be overwritten by the Java or IOS configuration.
-        bundle_policy = kBundlePolicyMaxBundle;
-        rtcp_mux_policy = kRtcpMuxPolicyRequire;
-        ice_connection_receiving_timeout =
-            kAggressiveIceConnectionReceivingTimeout;
-
-        // These parameters are not defined in Java or IOS configuration,
-        // so their values will not be overwritten.
-        enable_ice_renomination = true;
-        redetermine_role_on_ice_restart = false;
-      }
-    }
+    RTCConfiguration();
+    RTCConfiguration(const RTCConfiguration&);
+    explicit RTCConfiguration(RTCConfigurationType type);
+    ~RTCConfiguration();
 
     bool operator==(const RTCConfiguration& o) const;
     bool operator!=(const RTCConfiguration& o) const;
@@ -668,7 +660,7 @@
   // - INVALID_STATE: The PeerConnection is closed.
   virtual RTCErrorOr<rtc::scoped_refptr<RtpSenderInterface>> AddTrack(
       rtc::scoped_refptr<MediaStreamTrackInterface> track,
-      const std::vector<std::string>& stream_ids) = 0;
+      const std::vector<std::string>& stream_ids);
 
   // Remove an RtpSender from this PeerConnection.
   // Returns true on success.
@@ -701,14 +693,10 @@
   // Errors:
   // - INVALID_PARAMETER: |track| is null.
   virtual RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
-  AddTransceiver(rtc::scoped_refptr<MediaStreamTrackInterface> track) {
-    return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
-  }
+  AddTransceiver(rtc::scoped_refptr<MediaStreamTrackInterface> track);
   virtual RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
   AddTransceiver(rtc::scoped_refptr<MediaStreamTrackInterface> track,
-                 const RtpTransceiverInit& init) {
-    return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
-  }
+                 const RtpTransceiverInit& init);
 
   // Adds a transceiver with the given kind. Can either be MEDIA_TYPE_AUDIO or
   // MEDIA_TYPE_VIDEO.
@@ -716,14 +704,9 @@
   // - INVALID_PARAMETER: |media_type| is not MEDIA_TYPE_AUDIO or
   //                      MEDIA_TYPE_VIDEO.
   virtual RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
-  AddTransceiver(cricket::MediaType media_type) {
-    return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
-  }
+  AddTransceiver(cricket::MediaType media_type);
   virtual RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>
-  AddTransceiver(cricket::MediaType media_type,
-                 const RtpTransceiverInit& init) {
-    return RTCError(RTCErrorType::INTERNAL_ERROR, "not implemented");
-  }
+  AddTransceiver(cricket::MediaType media_type, const RtpTransceiverInit& init);
 
   // TODO(deadbeef): Make these pure virtual once all subclasses implement them.
 
@@ -743,9 +726,7 @@
   // AddTransceiver instead.
   virtual rtc::scoped_refptr<RtpSenderInterface> CreateSender(
       const std::string& kind,
-      const std::string& stream_id) {
-    return rtc::scoped_refptr<RtpSenderInterface>();
-  }
+      const std::string& stream_id);
 
   // If Plan B semantics are specified, gets all RtpSenders, created either
   // through AddStream, AddTrack, or CreateSender. All senders of a specific
@@ -754,9 +735,7 @@
   // If Unified Plan semantics are specified, gets the RtpSender for each
   // RtpTransceiver.
   virtual std::vector<rtc::scoped_refptr<RtpSenderInterface>> GetSenders()
-      const {
-    return std::vector<rtc::scoped_refptr<RtpSenderInterface>>();
-  }
+      const;
 
   // If Plan B semantics are specified, gets all RtpReceivers created when a
   // remote description is applied. All receivers of a specific media type share
@@ -767,9 +746,7 @@
   // If Unified Plan semantics are specified, gets the RtpReceiver for each
   // RtpTransceiver.
   virtual std::vector<rtc::scoped_refptr<RtpReceiverInterface>> GetReceivers()
-      const {
-    return std::vector<rtc::scoped_refptr<RtpReceiverInterface>>();
-  }
+      const;
 
   // Get all RtpTransceivers, created either through AddTransceiver, AddTrack or
   // by a remote description applied with SetRemoteDescription.
@@ -777,9 +754,7 @@
   // Note: This method is only available when Unified Plan is enabled (see
   // RTCConfiguration).
   virtual std::vector<rtc::scoped_refptr<RtpTransceiverInterface>>
-  GetTransceivers() const {
-    return {};
-  }
+  GetTransceivers() const;
 
   // The legacy non-compliant GetStats() API. This correspond to the
   // callback-based version of getStats() in JavaScript. The returned metrics
@@ -844,24 +819,14 @@
 
   // A "current" description the one currently negotiated from a complete
   // offer/answer exchange.
-  virtual const SessionDescriptionInterface* current_local_description() const {
-    return nullptr;
-  }
-  virtual const SessionDescriptionInterface* current_remote_description()
-      const {
-    return nullptr;
-  }
+  virtual const SessionDescriptionInterface* current_local_description() const;
+  virtual const SessionDescriptionInterface* current_remote_description() const;
 
   // A "pending" description is one that's part of an incomplete offer/answer
   // exchange (thus, either an offer or a pranswer). Once the offer/answer
   // exchange is finished, the "pending" description will become "current".
-  virtual const SessionDescriptionInterface* pending_local_description() const {
-    return nullptr;
-  }
-  virtual const SessionDescriptionInterface* pending_remote_description()
-      const {
-    return nullptr;
-  }
+  virtual const SessionDescriptionInterface* pending_local_description() const;
+  virtual const SessionDescriptionInterface* pending_remote_description() const;
 
   // Create a new offer.
   // The CreateSessionDescriptionObserver callback will be called when done.
@@ -903,9 +868,7 @@
 
   // TODO(deadbeef): Make this pure virtual once all Chrome subclasses of
   // PeerConnectionInterface implement it.
-  virtual PeerConnectionInterface::RTCConfiguration GetConfiguration() {
-    return PeerConnectionInterface::RTCConfiguration();
-  }
+  virtual PeerConnectionInterface::RTCConfiguration GetConfiguration();
 
   // Sets the PeerConnection's global configuration to |config|.
   //
@@ -932,15 +895,12 @@
   // PeerConnectionInterface implement it.
   virtual bool SetConfiguration(
       const PeerConnectionInterface::RTCConfiguration& config,
-      RTCError* error) {
-    return false;
-  }
+      RTCError* error);
+
   // Version without error output param for backwards compatibility.
   // TODO(deadbeef): Remove once chromium is updated.
   virtual bool SetConfiguration(
-      const PeerConnectionInterface::RTCConfiguration& config) {
-    return false;
-  }
+      const PeerConnectionInterface::RTCConfiguration& config);
 
   // Provides a remote candidate to the ICE Agent.
   // A copy of the |candidate| will be created and added to the remote
@@ -952,9 +912,7 @@
   // continual gathering, to avoid an ever-growing list of candidates as
   // networks come and go.
   virtual bool RemoveIceCandidates(
-      const std::vector<cricket::Candidate>& candidates) {
-    return false;
-  }
+      const std::vector<cricket::Candidate>& candidates);
 
   // Register a metric observer (used by chromium). It's reference counted, and
   // this method takes a reference. RegisterUMAObserver(nullptr) will release
@@ -967,6 +925,9 @@
 
   // 0 <= min <= current <= max should hold for set parameters.
   struct BitrateParameters {
+    BitrateParameters();
+    ~BitrateParameters();
+
     absl::optional<int> min_bitrate_bps;
     absl::optional<int> current_bitrate_bps;
     absl::optional<int> max_bitrate_bps;
@@ -978,24 +939,12 @@
   //
   // Setting |current_bitrate_bps| will reset the current bitrate estimate
   // to the provided value.
-  virtual RTCError SetBitrate(const BitrateSettings& bitrate) {
-    BitrateParameters bitrate_parameters;
-    bitrate_parameters.min_bitrate_bps = bitrate.min_bitrate_bps;
-    bitrate_parameters.current_bitrate_bps = bitrate.start_bitrate_bps;
-    bitrate_parameters.max_bitrate_bps = bitrate.max_bitrate_bps;
-    return SetBitrate(bitrate_parameters);
-  }
+  virtual RTCError SetBitrate(const BitrateSettings& bitrate);
 
   // TODO(nisse): Deprecated - use version above. These two default
   // implementations require subclasses to implement one or the other
   // of the methods.
-  virtual RTCError SetBitrate(const BitrateParameters& bitrate_parameters) {
-    BitrateSettings bitrate;
-    bitrate.min_bitrate_bps = bitrate_parameters.min_bitrate_bps;
-    bitrate.start_bitrate_bps = bitrate_parameters.current_bitrate_bps;
-    bitrate.max_bitrate_bps = bitrate_parameters.max_bitrate_bps;
-    return SetBitrate(bitrate);
-  }
+  virtual RTCError SetBitrate(const BitrateParameters& bitrate_parameters);
 
   // Sets current strategy. If not set default WebRTC allocator will be used.
   // May be changed during an active session. The strategy
@@ -1037,19 +986,14 @@
   // automatically after 10 minutes have passed, or when the StopRtcEventLog
   // function is called.
   // TODO(eladalon): Deprecate and remove this.
-  virtual bool StartRtcEventLog(rtc::PlatformFile file,
-                                int64_t max_size_bytes) {
-    return false;
-  }
+  virtual bool StartRtcEventLog(rtc::PlatformFile file, int64_t max_size_bytes);
 
   // Start RtcEventLog using an existing output-sink. Takes ownership of
   // |output| and passes it on to Call, which will take the ownership. If the
   // operation fails the output will be closed and deallocated. The event log
   // will send serialized events to the output object every |output_period_ms|.
   virtual bool StartRtcEventLog(std::unique_ptr<RtcEventLogOutput> output,
-                                int64_t output_period_ms) {
-    return false;
-  }
+                                int64_t output_period_ms);
 
   // Stops logging the RtcEventLog.
   // TODO(ivoc): Make this pure virtual when Chrome is updated.
@@ -1065,7 +1009,7 @@
 
  protected:
   // Dtor protected as objects shouldn't be deleted via this interface.
-  ~PeerConnectionInterface() {}
+  ~PeerConnectionInterface() override = default;
 };
 
 // PeerConnection callback interface, used for RTCPeerConnection events.
@@ -1159,15 +1103,15 @@
 // PeerConnection object to be the definitive owner of the dependencies
 // lifetime making injection safer.
 struct PeerConnectionDependencies final {
-  explicit PeerConnectionDependencies(PeerConnectionObserver* observer_in)
-      : observer(observer_in) {}
+  explicit PeerConnectionDependencies(PeerConnectionObserver* observer_in);
   // This object is not copyable or assignable.
   PeerConnectionDependencies(const PeerConnectionDependencies&) = delete;
   PeerConnectionDependencies& operator=(const PeerConnectionDependencies&) =
       delete;
   // This object is only moveable.
-  PeerConnectionDependencies(PeerConnectionDependencies&&) = default;
+  PeerConnectionDependencies(PeerConnectionDependencies&&);
   PeerConnectionDependencies& operator=(PeerConnectionDependencies&&) = default;
+  ~PeerConnectionDependencies();
   // Mandatory dependencies
   PeerConnectionObserver* observer = nullptr;
   // Optional dependencies
@@ -1183,17 +1127,17 @@
 // connection factory to take ownership of the dependency by adding a unique_ptr
 // to this structure.
 struct PeerConnectionFactoryDependencies final {
-  PeerConnectionFactoryDependencies() = default;
+  PeerConnectionFactoryDependencies();
   // This object is not copyable or assignable.
   PeerConnectionFactoryDependencies(const PeerConnectionFactoryDependencies&) =
       delete;
   PeerConnectionFactoryDependencies& operator=(
       const PeerConnectionFactoryDependencies&) = delete;
   // This object is only moveable.
-  PeerConnectionFactoryDependencies(PeerConnectionFactoryDependencies&&) =
-      default;
+  PeerConnectionFactoryDependencies(PeerConnectionFactoryDependencies&&);
   PeerConnectionFactoryDependencies& operator=(
       PeerConnectionFactoryDependencies&&) = default;
+  ~PeerConnectionFactoryDependencies();
 
   // Optional dependencies
   rtc::Thread* network_thread = nullptr;
@@ -1264,9 +1208,7 @@
   // are updated.
   virtual rtc::scoped_refptr<PeerConnectionInterface> CreatePeerConnection(
       const PeerConnectionInterface::RTCConfiguration& configuration,
-      PeerConnectionDependencies dependencies) {
-    return nullptr;
-  }
+      PeerConnectionDependencies dependencies);
 
   // Deprecated; |allocator| and |cert_generator| may be null, in which case
   // default implementations will be used.
@@ -1281,9 +1223,8 @@
       const PeerConnectionInterface::RTCConfiguration& configuration,
       std::unique_ptr<cricket::PortAllocator> allocator,
       std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator,
-      PeerConnectionObserver* observer) {
-    return nullptr;
-  }
+      PeerConnectionObserver* observer);
+
   // Deprecated; should use RTCConfiguration for everything that previously
   // used constraints.
   virtual rtc::scoped_refptr<PeerConnectionInterface> CreatePeerConnection(
@@ -1291,25 +1232,19 @@
       const MediaConstraintsInterface* constraints,
       std::unique_ptr<cricket::PortAllocator> allocator,
       std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator,
-      PeerConnectionObserver* observer) {
-    return nullptr;
-  }
+      PeerConnectionObserver* observer);
 
   // Returns the capabilities of an RTP sender of type |kind|.
   // If for some reason you pass in MEDIA_TYPE_DATA, returns an empty structure.
   // TODO(orphis): Make pure virtual when all subclasses implement it.
   virtual RtpCapabilities GetRtpSenderCapabilities(
-      cricket::MediaType kind) const {
-    return {};
-  }
+      cricket::MediaType kind) const;
 
   // Returns the capabilities of an RTP receiver of type |kind|.
   // If for some reason you pass in MEDIA_TYPE_DATA, returns an empty structure.
   // TODO(orphis): Make pure virtual when all subclasses implement it.
   virtual RtpCapabilities GetRtpReceiverCapabilities(
-      cricket::MediaType kind) const {
-    return {};
-  }
+      cricket::MediaType kind) const;
 
   virtual rtc::scoped_refptr<MediaStreamInterface> CreateLocalMediaStream(
       const std::string& stream_id) = 0;
@@ -1327,9 +1262,7 @@
   // TODO(deadbeef): Make pure virtual once downstream mock PC factory classes
   // are updated.
   virtual rtc::scoped_refptr<VideoTrackSourceInterface> CreateVideoSource(
-      std::unique_ptr<cricket::VideoCapturer> capturer) {
-    return nullptr;
-  }
+      std::unique_ptr<cricket::VideoCapturer> capturer);
 
   // A video source creator that allows selection of resolution and frame rate.
   // |constraints| decides video resolution and frame rate but can be null.
@@ -1339,22 +1272,15 @@
   // safely be destroyed afterwards.
   virtual rtc::scoped_refptr<VideoTrackSourceInterface> CreateVideoSource(
       std::unique_ptr<cricket::VideoCapturer> capturer,
-      const MediaConstraintsInterface* constraints) {
-    return nullptr;
-  }
+      const MediaConstraintsInterface* constraints);
 
   // Deprecated; please use the versions that take unique_ptrs above.
   // TODO(deadbeef): Remove these once safe to do so.
   virtual rtc::scoped_refptr<VideoTrackSourceInterface> CreateVideoSource(
-      cricket::VideoCapturer* capturer) {
-    return CreateVideoSource(std::unique_ptr<cricket::VideoCapturer>(capturer));
-  }
+      cricket::VideoCapturer* capturer);
   virtual rtc::scoped_refptr<VideoTrackSourceInterface> CreateVideoSource(
       cricket::VideoCapturer* capturer,
-      const MediaConstraintsInterface* constraints) {
-    return CreateVideoSource(std::unique_ptr<cricket::VideoCapturer>(capturer),
-                             constraints);
-  }
+      const MediaConstraintsInterface* constraints);
 
   // Creates a new local VideoTrack. The same |source| can be used in several
   // tracks.
@@ -1383,7 +1309,7 @@
   // Dtor and ctor protected as objects shouldn't be created or deleted via
   // this interface.
   PeerConnectionFactoryInterface() {}
-  ~PeerConnectionFactoryInterface() {}  // NOLINT
+  ~PeerConnectionFactoryInterface() override = default;
 };
 
 // Create a new instance of PeerConnectionFactoryInterface.
diff --git a/api/rtpsenderinterface.h b/api/rtpsenderinterface.h
index 6003aa0..a7eec49 100644
--- a/api/rtpsenderinterface.h
+++ b/api/rtpsenderinterface.h
@@ -64,7 +64,7 @@
   virtual rtc::scoped_refptr<DtmfSenderInterface> GetDtmfSender() const = 0;
 
  protected:
-  virtual ~RtpSenderInterface() {}
+  ~RtpSenderInterface() override = default;
 };
 
 // Define proxy for RtpSenderInterface.
diff --git a/api/rtptransceiverinterface.cc b/api/rtptransceiverinterface.cc
new file mode 100644
index 0000000..7f94c75
--- /dev/null
+++ b/api/rtptransceiverinterface.cc
@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "api/rtptransceiverinterface.h"
+
+namespace webrtc {
+
+RtpTransceiverInit::RtpTransceiverInit() = default;
+
+RtpTransceiverInit::~RtpTransceiverInit() = default;
+
+absl::optional<RtpTransceiverDirection>
+RtpTransceiverInterface::fired_direction() const {
+  return absl::nullopt;
+}
+
+}  // namespace webrtc
diff --git a/api/rtptransceiverinterface.h b/api/rtptransceiverinterface.h
index 26f1fdf..025e8e3 100644
--- a/api/rtptransceiverinterface.h
+++ b/api/rtptransceiverinterface.h
@@ -34,6 +34,8 @@
 // PeerConnectionInterface::AddTransceiver.
 // https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiverinit
 struct RtpTransceiverInit final {
+  RtpTransceiverInit();
+  ~RtpTransceiverInit();
   // Direction of the RtpTransceiver. See RtpTransceiverInterface::direction().
   RtpTransceiverDirection direction = RtpTransceiverDirection::kSendRecv;
 
@@ -112,9 +114,7 @@
   // OnAddTrack only get fired once even if the same session description is
   // applied again.
   // Exposed in the public interface for use by Chromium.
-  virtual absl::optional<RtpTransceiverDirection> fired_direction() const {
-    return absl::nullopt;
-  }
+  virtual absl::optional<RtpTransceiverDirection> fired_direction() const;
 
   // The Stop method irreversibly stops the RtpTransceiver. The sender of this
   // transceiver will no longer send, the receiver will no longer receive.
@@ -129,7 +129,7 @@
       rtc::ArrayView<RtpCodecCapability> codecs) = 0;
 
  protected:
-  virtual ~RtpTransceiverInterface() = default;
+  ~RtpTransceiverInterface() override = default;
 };
 
 }  // namespace webrtc
diff --git a/api/stats/rtcstatscollectorcallback.h b/api/stats/rtcstatscollectorcallback.h
index 2c67bb8..9242217 100644
--- a/api/stats/rtcstatscollectorcallback.h
+++ b/api/stats/rtcstatscollectorcallback.h
@@ -19,7 +19,7 @@
 
 class RTCStatsCollectorCallback : public virtual rtc::RefCountInterface {
  public:
-  virtual ~RTCStatsCollectorCallback() {}
+  ~RTCStatsCollectorCallback() override = default;
 
   virtual void OnStatsDelivered(
       const rtc::scoped_refptr<const RTCStatsReport>& report) = 0;
diff --git a/media/base/videocapturer.cc b/media/base/videocapturer.cc
index a03f903..643134c 100644
--- a/media/base/videocapturer.cc
+++ b/media/base/videocapturer.cc
@@ -40,6 +40,8 @@
   Construct();
 }
 
+VideoCapturer::~VideoCapturer() {}
+
 void VideoCapturer::Construct() {
   enable_camera_list_ = false;
   capture_state_ = CS_STOPPED;
@@ -65,6 +67,10 @@
   return true;
 }
 
+bool VideoCapturer::apply_rotation() {
+  return apply_rotation_;
+}
+
 void VideoCapturer::SetSupportedFormats(
     const std::vector<VideoFormat>& formats) {
   // This method is OK to call during initialization on a separate thread.
diff --git a/media/base/videocapturer.h b/media/base/videocapturer.h
index ee2f5ca..84f9565 100644
--- a/media/base/videocapturer.h
+++ b/media/base/videocapturer.h
@@ -77,7 +77,7 @@
  public:
   VideoCapturer();
 
-  virtual ~VideoCapturer() {}
+  ~VideoCapturer() override;
 
   // Gets the id of the underlying device, which is available after the capturer
   // is initialized. Can be used to determine if two capturers reference the
@@ -134,7 +134,7 @@
   virtual bool IsRunning() = 0;
   CaptureState capture_state() const { return capture_state_; }
 
-  virtual bool apply_rotation() { return apply_rotation_; }
+  virtual bool apply_rotation();
 
   // Returns true if the capturer is screencasting. This can be used to
   // implement screencast specific behavior.