Refactor VideoTracks to forward all sinks to its source

webrtc/api/videotrack_unittest.cc

Index: webrtc/api/videotrack_unittest.cc
diff --git a/webrtc/api/videotrack_unittest.cc b/webrtc/api/videotrack_unittest.cc
index 008ba2181fa33cf84c44c88bfb7c8e6572679bc7..6dac507020321b1abd6f0f9866791247fa577a0e 100644
--- a/webrtc/api/videotrack_unittest.cc
+++ b/webrtc/api/videotrack_unittest.cc
@@ -61,9 +61,8 @@ TEST_F(VideoTrackTest, RenderVideo) {
   EXPECT_EQ(2, renderer_1->num_rendered_frames());
   EXPECT_EQ(1, renderer_2->num_rendered_frames());
 
-  video_track_->RemoveSink(renderer_1.get());
+  renderer_1.reset(nullptr);
   capturer_.CaptureFrame();
-  EXPECT_EQ(2, renderer_1->num_rendered_frames());
   EXPECT_EQ(2, renderer_2->num_rendered_frames());
 }
 
@@ -86,9 +85,8 @@ TEST_F(VideoTrackTest, RenderVideoOld) {
   EXPECT_EQ(2, renderer_1->num_rendered_frames());
   EXPECT_EQ(1, renderer_2->num_rendered_frames());
 
-  video_track_->RemoveRenderer(renderer_1.get());
+  renderer_1.reset(nullptr);
   capturer_.CaptureFrame();
-  EXPECT_EQ(2, renderer_1->num_rendered_frames());
   EXPECT_EQ(2, renderer_2->num_rendered_frames());
 }