MediaRecorder: make MediaRecorderHandler a MediaStreamObserver

content/renderer/media/media_recorder_handler.h

Index: content/renderer/media/media_recorder_handler.h
diff --git a/content/renderer/media/media_recorder_handler.h b/content/renderer/media/media_recorder_handler.h
index cc50c84ee84c9a371a423581f5faa614f16a9dca..6de4ebe0486607d9a55a497d9a61fc7e3435a3bb 100644
--- a/content/renderer/media/media_recorder_handler.h
+++ b/content/renderer/media/media_recorder_handler.h
@@ -12,6 +12,7 @@
 #include "base/strings/string_piece.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
+#include "content/renderer/media/media_stream.h"
 #include "third_party/WebKit/public/platform/WebMediaRecorderHandler.h"
 #include "third_party/WebKit/public/platform/WebMediaStream.h"
 
@@ -42,7 +43,8 @@ class AudioTrackRecorder;
 // i.e. the Main Render thread. (Note that a BindToCurrentLoop is used to
 // guarantee this, since VideoTrackRecorder sends back frames on IO thread.)
 class CONTENT_EXPORT MediaRecorderHandler final
-    : public NON_EXPORTED_BASE(blink::WebMediaRecorderHandler) {
+    : public NON_EXPORTED_BASE(blink::WebMediaRecorderHandler),
+      public NON_EXPORTED_BASE(MediaStreamObserver) {
  public:
   MediaRecorderHandler();
   ~MediaRecorderHandler() override;
@@ -51,7 +53,7 @@ class CONTENT_EXPORT MediaRecorderHandler final
   bool canSupportMimeType(const blink::WebString& web_type,
                           const blink::WebString& web_codecs) override;
   bool initialize(blink::WebMediaRecorderHandlerClient* client,
-                  const blink::WebMediaStream& media_stream,
+                  const blink::WebMediaStream& web_media_stream,
                   const blink::WebString& type,
                   const blink::WebString& codecs) override;
   bool start() override;
@@ -60,6 +62,11 @@ class CONTENT_EXPORT MediaRecorderHandler final
   void pause() override;
   void resume() override;
 
+  // MediaStreamObserver implementation. On MS modification, we stop recording
+  // and signal this illegal condition to |client_|.
+  void TrackAdded(const blink::WebMediaStreamTrack& track) override;
+  void TrackRemoved(const blink::WebMediaStreamTrack& track) override;
+
  private:
   friend class MediaRecorderHandlerTest;
 
@@ -91,7 +98,7 @@ class CONTENT_EXPORT MediaRecorderHandler final
   base::TimeTicks slice_origin_timestamp_;
 
   bool recording_;
-  blink::WebMediaStream media_stream_;  // The MediaStream being recorded.
+  blink::WebMediaStream web_media_stream_;  // WebMediaStream being recorded.
 
   // |client_| is a weak pointer, and is valid for the lifetime of this object.
   blink::WebMediaRecorderHandlerClient* client_;