Move MediaConfig to its own header file and target.

To eliminate circular dependencies, we need to eliminate the include
of media/base/mediachannel.h from api/peerconnectioninterface.h.

MediaConfig is one of the types the PeerConnection api depends on,
since it's part of PeerConnectionInterface::RTCConfiguration. It's
formally a public member, but the intention is that applications should use
accessor mehtods on RTCConfiguration and never access the contents of
MediaConfig directly.

Bug: webrtc:7504
Change-Id: Idfab6f69132d6b90d1628fa4543a393e22db79ac
Reviewed-on: https://webrtc-review.googlesource.com/41260
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21731}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index 95891df..e9eba77 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -103,6 +103,7 @@
     # file, really. All these should arguably go away in time.
     "..:typedefs",
     "..:webrtc_common",
+    "../media:rtc_media_config",
     "../modules/audio_processing:audio_processing_statistics",
     "../rtc_base:checks",
     "../rtc_base:deprecation",
diff --git a/api/peerconnectioninterface.h b/api/peerconnectioninterface.h
index 3cbf263..7087de6 100644
--- a/api/peerconnectioninterface.h
+++ b/api/peerconnectioninterface.h
@@ -95,7 +95,7 @@
 #include "api/umametrics.h"
 #include "call/callfactoryinterface.h"
 #include "logging/rtc_event_log/rtc_event_log_factory_interface.h"
-#include "media/base/mediachannel.h"
+#include "media/base/mediaconfig.h"
 #include "media/base/videocapturer.h"
 #include "p2p/base/portallocator.h"
 #include "rtc_base/network.h"
@@ -446,6 +446,9 @@
     // standard priority order.
     bool prioritize_most_likely_ice_candidate_pairs = false;
 
+    // Implementation defined settings. A public member only for the benefit of
+    // the implementation. Applications must not access it directly, and should
+    // instead use provided accessor methods, e.g., set_cpu_adaptation.
     struct cricket::MediaConfig media_config;
 
     // If set to true, only one preferred TURN allocation will be used per
diff --git a/media/BUILD.gn b/media/BUILD.gn
index dfadbae..b856bb5 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -55,6 +55,13 @@
   ]
 }
 
+rtc_source_set("rtc_media_config") {
+  visibility = [ "*" ]
+  sources = [
+    "base/mediaconfig.h",
+  ]
+}
+
 rtc_static_library("rtc_media_base") {
   visibility = [ "*" ]
   defines = []
@@ -106,6 +113,7 @@
 
   deps += [
     ":rtc_h264_profile_id",
+    ":rtc_media_config",
     "..:webrtc_common",
     "../api:libjingle_peerconnection_api",
     "../api:optional",
diff --git a/media/base/mediachannel.h b/media/base/mediachannel.h
index 3bcb596..32ab479 100644
--- a/media/base/mediachannel.h
+++ b/media/base/mediachannel.h
@@ -28,6 +28,7 @@
 #include "api/videosourceinterface.h"
 #include "call/video_config.h"
 #include "media/base/codec.h"
+#include "media/base/mediaconfig.h"
 #include "media/base/mediaconstants.h"
 #include "media/base/streamparams.h"
 #include "modules/audio_processing/include/audio_processing_statistics.h"
@@ -88,71 +89,6 @@
     return ost.str();
 }
 
-// Construction-time settings, passed on when creating
-// MediaChannels.
-struct MediaConfig {
-  // Set DSCP value on packets. This flag comes from the
-  // PeerConnection constraint 'googDscp'.
-  bool enable_dscp = false;
-
-  // Video-specific config.
-  struct Video {
-    // Enable WebRTC CPU Overuse Detection. This flag comes from the
-    // PeerConnection constraint 'googCpuOveruseDetection'.
-    bool enable_cpu_adaptation = true;
-
-    // Enable WebRTC suspension of video. No video frames will be sent
-    // when the bitrate is below the configured minimum bitrate. This
-    // flag comes from the PeerConnection constraint
-    // 'googSuspendBelowMinBitrate', and WebRtcVideoChannel copies it
-    // to VideoSendStream::Config::suspend_below_min_bitrate.
-    bool suspend_below_min_bitrate = false;
-
-    // Set to true if the renderer has an algorithm of frame selection.
-    // If the value is true, then WebRTC will hand over a frame as soon as
-    // possible without delay, and rendering smoothness is completely the duty
-    // of the renderer;
-    // If the value is false, then WebRTC is responsible to delay frame release
-    // in order to increase rendering smoothness.
-    //
-    // This flag comes from PeerConnection's RtcConfiguration, but is
-    // currently only set by the command line flag
-    // 'disable-rtc-smoothness-algorithm'.
-    // WebRtcVideoChannel::AddRecvStream copies it to the created
-    // WebRtcVideoReceiveStream, where it is returned by the
-    // SmoothsRenderedFrames method. This method is used by the
-    // VideoReceiveStream, where the value is passed on to the
-    // IncomingVideoStream constructor.
-    bool enable_prerenderer_smoothing = true;
-
-    // Enables periodic bandwidth probing in application-limited region.
-    bool periodic_alr_bandwidth_probing = false;
-
-    // Enables the new method to estimate the cpu load from encoding, used for
-    // cpu adaptation. This flag is intended to be controlled primarily by a
-    // Chrome origin-trial.
-    // TODO(bugs.webrtc.org/8504): If all goes well, the flag will be removed
-    // together with the old method of estimation.
-    bool experiment_cpu_load_estimator = false;
-  } video;
-
-  bool operator==(const MediaConfig& o) const {
-    return enable_dscp == o.enable_dscp &&
-           video.enable_cpu_adaptation ==
-               o.video.enable_cpu_adaptation &&
-           video.suspend_below_min_bitrate ==
-               o.video.suspend_below_min_bitrate &&
-           video.enable_prerenderer_smoothing ==
-               o.video.enable_prerenderer_smoothing &&
-           video.periodic_alr_bandwidth_probing ==
-               o.video.periodic_alr_bandwidth_probing &&
-           video.experiment_cpu_load_estimator ==
-               o.video.experiment_cpu_load_estimator;
-  }
-
-  bool operator!=(const MediaConfig& o) const { return !(*this == o); }
-};
-
 // Options that can be applied to a VideoMediaChannel or a VideoMediaEngine.
 // Used to be flags, but that makes it hard to selectively apply options.
 // We are moving all of the setting of options to structs like this,
diff --git a/media/base/mediaconfig.h b/media/base/mediaconfig.h
new file mode 100644
index 0000000..5e84871
--- /dev/null
+++ b/media/base/mediaconfig.h
@@ -0,0 +1,83 @@
+/*
+ *  Copyright (c) 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.
+ */
+
+#ifndef MEDIA_BASE_MEDIACONFIG_H_
+#define MEDIA_BASE_MEDIACONFIG_H_
+
+namespace cricket {
+
+// Construction-time settings, passed on when creating
+// MediaChannels.
+struct MediaConfig {
+  // Set DSCP value on packets. This flag comes from the
+  // PeerConnection constraint 'googDscp'.
+  bool enable_dscp = false;
+
+  // Video-specific config.
+  struct Video {
+    // Enable WebRTC CPU Overuse Detection. This flag comes from the
+    // PeerConnection constraint 'googCpuOveruseDetection'.
+    bool enable_cpu_adaptation = true;
+
+    // Enable WebRTC suspension of video. No video frames will be sent
+    // when the bitrate is below the configured minimum bitrate. This
+    // flag comes from the PeerConnection constraint
+    // 'googSuspendBelowMinBitrate', and WebRtcVideoChannel copies it
+    // to VideoSendStream::Config::suspend_below_min_bitrate.
+    bool suspend_below_min_bitrate = false;
+
+    // Set to true if the renderer has an algorithm of frame selection.
+    // If the value is true, then WebRTC will hand over a frame as soon as
+    // possible without delay, and rendering smoothness is completely the duty
+    // of the renderer;
+    // If the value is false, then WebRTC is responsible to delay frame release
+    // in order to increase rendering smoothness.
+    //
+    // This flag comes from PeerConnection's RtcConfiguration, but is
+    // currently only set by the command line flag
+    // 'disable-rtc-smoothness-algorithm'.
+    // WebRtcVideoChannel::AddRecvStream copies it to the created
+    // WebRtcVideoReceiveStream, where it is returned by the
+    // SmoothsRenderedFrames method. This method is used by the
+    // VideoReceiveStream, where the value is passed on to the
+    // IncomingVideoStream constructor.
+    bool enable_prerenderer_smoothing = true;
+
+    // Enables periodic bandwidth probing in application-limited region.
+    bool periodic_alr_bandwidth_probing = false;
+
+    // Enables the new method to estimate the cpu load from encoding, used for
+    // cpu adaptation. This flag is intended to be controlled primarily by a
+    // Chrome origin-trial.
+    // TODO(bugs.webrtc.org/8504): If all goes well, the flag will be removed
+    // together with the old method of estimation.
+    bool experiment_cpu_load_estimator = false;
+  } video;
+
+  bool operator==(const MediaConfig& o) const {
+    return enable_dscp == o.enable_dscp &&
+           video.enable_cpu_adaptation ==
+               o.video.enable_cpu_adaptation &&
+           video.suspend_below_min_bitrate ==
+               o.video.suspend_below_min_bitrate &&
+           video.enable_prerenderer_smoothing ==
+               o.video.enable_prerenderer_smoothing &&
+           video.periodic_alr_bandwidth_probing ==
+               o.video.periodic_alr_bandwidth_probing &&
+           video.experiment_cpu_load_estimator ==
+               o.video.experiment_cpu_load_estimator;
+  }
+
+  bool operator!=(const MediaConfig& o) const { return !(*this == o); }
+};
+
+}  // namespace cricket
+
+#endif  // MEDIA_BASE_MEDIACONFIG_H_
diff --git a/pc/rtpsender.h b/pc/rtpsender.h
index 119d91f..1fd7b37 100644
--- a/pc/rtpsender.h
+++ b/pc/rtpsender.h
@@ -23,9 +23,8 @@
 #include "api/rtpsenderinterface.h"
 #include "rtc_base/basictypes.h"
 #include "rtc_base/criticalsection.h"
-// Adding 'nogncheck' to disable the gn include headers check to support modular
-// WebRTC build targets.
-#include "media/base/audiosource.h"  // nogncheck
+#include "media/base/audiosource.h"
+#include "media/base/mediachannel.h"
 #include "pc/dtmfsender.h"
 #include "pc/statscollector.h"