Change MediaStreamAudioTrack to operate over MediaStreamComponent

.... instead of WebMediaStreamTrack.

This is part of the effort to reduce the needless use of
public Blink APIs (wrappers) within renderer/modules.

BUG=704136
R=guidou@chromium.org

Change-Id: I5a6e683283b9a57f642a09d0f06410d2fde95690
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2239973
Auto-Submit: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Cr-Commit-Position: refs/heads/master@{#777989}

third_party/blink/renderer/platform/mediastream/media_stream_audio_track.cc

@@ -12,6 +12,8 @@
 #include "third_party/blink/public/platform/modules/mediastream/web_media_stream_audio_sink.h"
 #include "third_party/blink/public/platform/modules/webrtc/webrtc_logging.h"
 #include "third_party/blink/public/platform/web_media_stream_source.h"
+#include "third_party/blink/renderer/platform/mediastream/media_stream_component.h"
+#include "third_party/blink/renderer/platform/mediastream/media_stream_source.h"
 
 namespace blink {
 
@@ -38,12 +40,12 @@ MediaStreamAudioTrack::~MediaStreamAudioTrack() {
 
 // static
 MediaStreamAudioTrack* MediaStreamAudioTrack::From(
-    const WebMediaStreamTrack& track) {
-  if (track.IsNull() ||
-      track.Source().GetType() != WebMediaStreamSource::kTypeAudio) {
+    const MediaStreamComponent* component) {
+  if (!component ||
+      component->Source()->GetType() != MediaStreamSource::kTypeAudio) {
     return nullptr;
   }
-  return static_cast<MediaStreamAudioTrack*>(track.GetPlatformTrack());
+  return static_cast<MediaStreamAudioTrack*>(component->GetPlatformTrack());
 }
 
 void MediaStreamAudioTrack::AddSink(WebMediaStreamAudioSink* sink) {

third_party/blink/renderer/platform/mediastream/media_stream_audio_track.h

@@ -21,11 +21,12 @@ namespace blink {
 
 class WebMediaStreamAudioSink;
 class MediaStreamAudioSource;
+class MediaStreamComponent;
 
 // Provides the part of the audio pipeline delivering audio from a
 // MediaStreamAudioSource to one or more WebMediaStreamAudioSinks. An instance
-// of this class is owned by WebMediaStreamTrack, and clients should use
-// From() to gain access to a MediaStreamAudioTrack.
+// of this class is owned by MediaStreamComponent/WebMediaStreamTrack, and
+// clients should use From() to gain access to a MediaStreamAudioTrack.
 class PLATFORM_EXPORT MediaStreamAudioTrack
     : public WebPlatformMediaStreamTrack {
  public:
@@ -35,7 +36,7 @@ class PLATFORM_EXPORT MediaStreamAudioTrack
 
   // Returns the MediaStreamAudioTrack instance owned by the given blink |track|
   // or null.
-  static MediaStreamAudioTrack* From(const WebMediaStreamTrack& track);
+  static MediaStreamAudioTrack* From(const MediaStreamComponent* component);
 
   // Provides a weak reference to this MediaStreamAudioTrack which is
   // invalidated when Stop() is called. The weak pointer may only be