More tracing for audio rendering

content/renderer/media/webrtc_audio_device_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/webrtc_audio_device_impl.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
+#include "base/trace_event/trace_event.h"
 #include "base/win/windows_version.h"
 #include "content/renderer/media/webrtc/processed_local_audio_source.h"
 #include "content/renderer/media/webrtc_audio_renderer.h"
 #include "media/audio/sample_rates.h"
 #include "media/base/audio_bus.h"
 #include "media/base/audio_parameters.h"
 
 using media::AudioParameters;
 using media::ChannelLayout;
 
@@ skipping 67 matching lines @@
   int frames_per_10_ms = (sample_rate / 100);
   int bytes_per_sample = sizeof(render_buffer_[0]);
   // Client should always ask for 10ms.
   DCHECK_EQ(audio_bus->frames(), frames_per_10_ms);
 
   // Get 10ms audio and copy result to temporary byte buffer.
   int64_t elapsed_time_ms = -1;
   int64_t ntp_time_ms = -1;
   static const int kBitsPerByte = 8;
   int16_t* audio_data = &render_buffer_[0];
+
+  TRACE_EVENT_BEGIN0("audio", "VoE::PullRenderData");

[Henrik Grunell, 2016/08/22 08:29:06]

Nit: VoiceEngine is kind of an implementation detail. I suggest "Pull render
data from WebRTC". Wdyt?

   audio_transport_callback_->PullRenderData(
       bytes_per_sample * kBitsPerByte, sample_rate, audio_bus->channels(),
       frames_per_10_ms, audio_data, &elapsed_time_ms, &ntp_time_ms);
+  TRACE_EVENT_END0("audio", "VoE::PullRenderData");
   if (elapsed_time_ms >= 0) {
     *current_time = base::TimeDelta::FromMilliseconds(elapsed_time_ms);
   }
 
   // De-interleave each channel and convert to 32-bit floating-point
   // with nominal range -1.0 -> +1.0 to match the callback format.
   audio_bus->FromInterleaved(&render_buffer_[0],
                              audio_bus->frames(),
                              bytes_per_sample);
 
@@ skipping 377 matching lines @@
 
   *session_id = device_info.session_id;
   *output_sample_rate = device_info.device.matched_output.sample_rate;
   *output_frames_per_buffer =
       device_info.device.matched_output.frames_per_buffer;
 
   return true;
 }
 
 }  // namespace content