Remove voe::TransmitMixer

TransmitMixer's functionality is moved into the AudioTransportProxy
owned by AudioState. This removes the need for an AudioTransport
implementation in VoEBaseImpl, which means that the proxy is no longer
a proxy, hence AudioTransportProxy is renamed to AudioTransportImpl.

In the short term, AudioState needs to know which AudioDeviceModule is
used, so it is added in AudioState::Config. AudioTransportImpl needs
to know which AudioSendStream:s are currently enabled to send, so
AudioState maintains a map of them, which is reduced into a simple
vector for AudioTransportImpl.

To encode and transmit audio,
AudioSendStream::OnAudioData(std::unique_ptr<AudioFrame> audio_frame)
is introduced, which is used in both the Chromium and standalone use
cases. This removes the need for two different instances of
voe::Channel::ProcessAndEncodeAudio(), so there is now only one,
taking an AudioFrame as argument. Callers need to allocate their own
AudioFrame:s, which is wasteful but not a regression since this was
already happening in the voe::Channel functions.

Most of the logic changed resides in
AudioTransportImpl::RecordedDataIsAvailable(), where two strange
things were found:

  1. The clock drift parameter was ineffective since
     apm->echo_cancellation()->enable_drift_compensation(false) is
     called during initialization.

  2. The output parameter 'new_mic_volume' was never set - instead it
     was returned as a result, causing the ADM to never update the
     analog mic gain
     (https://cs.chromium.org/chromium/src/third_party/webrtc/voice_engine/voe_base_impl.cc?q=voe_base_impl.cc&dr&l=100).

Besides this, tests are updated, and some dead code is removed which
was found in the process.

Bug: webrtc:4690, webrtc:8591
Change-Id: I789d5296bf5efb7299a5ee05a4f3ce6abf9124b2
Reviewed-on: https://webrtc-review.googlesource.com/26681
Commit-Queue: Fredrik Solenberg <solenberg@webrtc.org>
Reviewed-by: Oskar Sundbom <ossu@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21301}
diff --git a/audio/audio_transport_impl.h b/audio/audio_transport_impl.h
new file mode 100644
index 0000000..e7de7e9
--- /dev/null
+++ b/audio/audio_transport_impl.h
@@ -0,0 +1,100 @@
+/*
+ *  Copyright (c) 2016 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 AUDIO_AUDIO_TRANSPORT_IMPL_H_
+#define AUDIO_AUDIO_TRANSPORT_IMPL_H_
+
+#include <vector>
+
+#include "api/audio/audio_mixer.h"
+#include "common_audio/resampler/include/push_resampler.h"
+#include "modules/audio_device/include/audio_device.h"
+#include "modules/audio_processing/include/audio_processing.h"
+#include "modules/audio_processing/typing_detection.h"
+#include "rtc_base/constructormagic.h"
+#include "rtc_base/criticalsection.h"
+#include "rtc_base/scoped_ref_ptr.h"
+#include "rtc_base/thread_annotations.h"
+#include "voice_engine/audio_level.h"
+
+namespace webrtc {
+
+class AudioSendStream;
+
+class AudioTransportImpl : public AudioTransport {
+ public:
+  AudioTransportImpl(AudioMixer* mixer,
+                     AudioProcessing* audio_processing,
+                     AudioDeviceModule* audio_device_module);
+  ~AudioTransportImpl() override;
+
+  int32_t RecordedDataIsAvailable(const void* audioSamples,
+                                  const size_t nSamples,
+                                  const size_t nBytesPerSample,
+                                  const size_t nChannels,
+                                  const uint32_t samplesPerSec,
+                                  const uint32_t totalDelayMS,
+                                  const int32_t clockDrift,
+                                  const uint32_t currentMicLevel,
+                                  const bool keyPressed,
+                                  uint32_t& newMicLevel) override;
+
+  int32_t NeedMorePlayData(const size_t nSamples,
+                           const size_t nBytesPerSample,
+                           const size_t nChannels,
+                           const uint32_t samplesPerSec,
+                           void* audioSamples,
+                           size_t& nSamplesOut,
+                           int64_t* elapsed_time_ms,
+                           int64_t* ntp_time_ms) override;
+
+  void PullRenderData(int bits_per_sample,
+                      int sample_rate,
+                      size_t number_of_channels,
+                      size_t number_of_frames,
+                      void* audio_data,
+                      int64_t* elapsed_time_ms,
+                      int64_t* ntp_time_ms) override;
+
+  void UpdateSendingStreams(std::vector<AudioSendStream*> streams,
+                            int send_sample_rate_hz, size_t send_num_channels);
+  void SetStereoChannelSwapping(bool enable);
+  bool typing_noise_detected() const;
+  const voe::AudioLevel& audio_level() const {
+    return audio_level_;
+  }
+
+ private:
+  // Shared.
+  AudioProcessing* audio_processing_ = nullptr;
+
+  // Capture side.
+  rtc::CriticalSection capture_lock_;
+  std::vector<AudioSendStream*> sending_streams_ RTC_GUARDED_BY(capture_lock_);
+  int send_sample_rate_hz_ RTC_GUARDED_BY(capture_lock_) = 8000;
+  size_t send_num_channels_ RTC_GUARDED_BY(capture_lock_) = 1;
+  bool typing_noise_detected_ RTC_GUARDED_BY(capture_lock_) = false;
+  bool swap_stereo_channels_ RTC_GUARDED_BY(capture_lock_) = false;
+  AudioDeviceModule* audio_device_module_ = nullptr;
+  PushResampler<int16_t> capture_resampler_;
+  voe::AudioLevel audio_level_;
+  TypingDetection typing_detection_;
+
+  // Render side.
+  rtc::scoped_refptr<AudioMixer> mixer_;
+  AudioFrame mixed_frame_;
+  // Converts mixed audio to the audio device output rate.
+  PushResampler<int16_t> render_resampler_;
+
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(AudioTransportImpl);
+};
+}  // namespace webrtc
+
+#endif  // AUDIO_AUDIO_TRANSPORT_IMPL_H_