Feed the WebRTC APM with empty far-end frames for the number of frames skipped by OS.

content/renderer/media/webrtc_audio_renderer_unittest.cc

Index: content/renderer/media/webrtc_audio_renderer_unittest.cc
diff --git a/content/renderer/media/webrtc_audio_renderer_unittest.cc b/content/renderer/media/webrtc_audio_renderer_unittest.cc
index 1468088390f8a819cea3775d70bc8e4cb292001b..46800617e131372e9f1c7f4612020f5373e08a7d 100644
--- a/content/renderer/media/webrtc_audio_renderer_unittest.cc
+++ b/content/renderer/media/webrtc_audio_renderer_unittest.cc
@@ -103,9 +103,10 @@ class MockAudioRendererSource : public WebRtcAudioRendererSource {
  public:
   MockAudioRendererSource() {}
   virtual ~MockAudioRendererSource() {}
-  MOCK_METHOD4(RenderData, void(media::AudioBus* audio_bus,
+  MOCK_METHOD5(RenderData, void(media::AudioBus* audio_bus,
                                 int sample_rate,
                                 int audio_delay_milliseconds,
+                                uint32_t skipped_frames,
                                 base::TimeDelta* current_time));
   MOCK_METHOD1(RemoveAudioRenderer, void(WebRtcAudioRenderer* renderer));
   MOCK_METHOD0(AudioRendererThreadStopped, void());