More tracing for audio rendering

media/base/audio_renderer_mixer_input.cc

Index: media/base/audio_renderer_mixer_input.cc
diff --git a/media/base/audio_renderer_mixer_input.cc b/media/base/audio_renderer_mixer_input.cc
index bf81747964931d33f0a2907392f42fd9bfae6184..a005b99178e8875596f7e83eb3cc93dd194d1f05 100644
--- a/media/base/audio_renderer_mixer_input.cc
+++ b/media/base/audio_renderer_mixer_input.cc
@@ -8,6 +8,7 @@
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
+#include "base/trace_event/trace_event.h"
 #include "media/base/audio_renderer_mixer.h"
 #include "media/base/audio_renderer_mixer_pool.h"
 
@@ -175,6 +176,7 @@ void AudioRendererMixerInput::SwitchOutputDevice(
 
 double AudioRendererMixerInput::ProvideInput(AudioBus* audio_bus,
                                              uint32_t frames_delayed) {
+  TRACE_EVENT0("audio", "AudioRendererMixerInput::ProvideInput");
   int frames_filled = callback_->Render(audio_bus, frames_delayed, 0);
 
   // AudioConverter expects unfilled frames to be zeroed.