Add unit tests for webrtc_media_stream_adapter.cc

content/renderer/media/mock_media_stream_registry.cc

Index: content/renderer/media/mock_media_stream_registry.cc
diff --git a/content/renderer/media/mock_media_stream_registry.cc b/content/renderer/media/mock_media_stream_registry.cc
index 0e89429d69d14abda45d52cf65090388bf1de8a6..f30a1e92f344d5e4080f957e4f415a05998db388 100644
--- a/content/renderer/media/mock_media_stream_registry.cc
+++ b/content/renderer/media/mock_media_stream_registry.cc
@@ -55,7 +55,9 @@ void MockMediaStreamRegistry::Init(const std::string& stream_url) {
   test_stream_.setExtraData(new MediaStream());
 }
 
-void MockMediaStreamRegistry::AddVideoTrack(const std::string& track_id) {
+void MockMediaStreamRegistry::AddVideoTrack(
+    const std::string& track_id,
+    const blink::WebMediaConstraints& constraints) {
   blink::WebMediaStreamSource blink_source;
   blink_source.initialize("mock video source id",
                           blink::WebMediaStreamSource::TypeVideo,
@@ -66,8 +68,6 @@ void MockMediaStreamRegistry::AddVideoTrack(const std::string& track_id) {
   blink_source.setExtraData(native_source);
   blink::WebMediaStreamTrack blink_track;
   blink_track.initialize(base::UTF8ToUTF16(track_id), blink_source);
-  blink::WebMediaConstraints constraints;
-  constraints.initialize();
 
   MediaStreamVideoTrack* native_track = new MediaStreamVideoTrack(
       native_source, constraints, MediaStreamVideoSource::ConstraintsCallback(),
@@ -76,6 +76,12 @@ void MockMediaStreamRegistry::AddVideoTrack(const std::string& track_id) {
   test_stream_.addTrack(blink_track);
 }
 
+void MockMediaStreamRegistry::AddVideoTrack(const std::string& track_id) {
+  blink::WebMediaConstraints constraints;
+  constraints.initialize();
+  AddVideoTrack(track_id, constraints);
+}
+
 void MockMediaStreamRegistry::AddAudioTrack(const std::string& track_id) {
   blink::WebMediaStreamSource blink_source;
   blink_source.initialize(