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_state.h b/audio/audio_state.h
index f4bddbf..14dc788 100644
--- a/audio/audio_state.h
+++ b/audio/audio_state.h
@@ -11,9 +11,10 @@
 #ifndef AUDIO_AUDIO_STATE_H_
 #define AUDIO_AUDIO_STATE_H_
 
+#include <map>
 #include <memory>
 
-#include "audio/audio_transport_proxy.h"
+#include "audio/audio_transport_impl.h"
 #include "audio/null_audio_poller.h"
 #include "audio/scoped_voe_interface.h"
 #include "call/audio_state.h"
@@ -24,6 +25,9 @@
 #include "voice_engine/include/voe_base.h"
 
 namespace webrtc {
+
+class AudioSendStream;
+
 namespace internal {
 
 class AudioState final : public webrtc::AudioState {
@@ -36,21 +40,30 @@
     return config_.audio_processing.get();
   }
   AudioTransport* audio_transport() override {
-    return &audio_transport_proxy_;
+    return &audio_transport_;
   }
 
   void SetPlayout(bool enabled) override;
   void SetRecording(bool enabled) override;
 
+  Stats GetAudioInputStats() const override;
+  void SetStereoChannelSwapping(bool enable) override;
+
   VoiceEngine* voice_engine();
   rtc::scoped_refptr<AudioMixer> mixer();
   bool typing_noise_detected() const;
 
+  void AddSendingStream(webrtc::AudioSendStream* stream,
+                        int sample_rate_hz, size_t num_channels);
+  void RemoveSendingStream(webrtc::AudioSendStream* stream);
+
  private:
   // rtc::RefCountInterface implementation.
   void AddRef() const override;
   rtc::RefCountReleaseStatus Release() const override;
 
+  void UpdateAudioTransportWithSendingStreams();
+
   rtc::ThreadChecker thread_checker_;
   rtc::ThreadChecker process_thread_checker_;
   const webrtc::AudioState::Config config_;
@@ -63,14 +76,20 @@
   mutable volatile int ref_count_ = 0;
 
   // Transports mixed audio from the mixer to the audio device and
-  // recorded audio to the VoE AudioTransport.
-  AudioTransportProxy audio_transport_proxy_;
+  // recorded audio to the sending streams.
+  AudioTransportImpl audio_transport_;
 
   // Null audio poller is used to continue polling the audio streams if audio
   // playout is disabled so that audio processing still happens and the audio
   // stats are still updated.
   std::unique_ptr<NullAudioPoller> null_audio_poller_;
 
+  struct StreamProperties {
+    int sample_rate_hz = 0;
+    size_t num_channels = 0;
+  };
+  std::map<webrtc::AudioSendStream*, StreamProperties> sending_streams_;
+
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(AudioState);
 };
 }  // namespace internal