Audio input traces for Mac (browser-side)

content/browser/renderer_host/media/audio_input_sync_writer.cc

Index: content/browser/renderer_host/media/audio_input_sync_writer.cc
diff --git a/content/browser/renderer_host/media/audio_input_sync_writer.cc b/content/browser/renderer_host/media/audio_input_sync_writer.cc
index e706934dfbcd52e3a517def4bfb8e41bfacb0520..3bed144059548ebb64b41e9091ce70976dd1272d 100644
--- a/content/browser/renderer_host/media/audio_input_sync_writer.cc
+++ b/content/browser/renderer_host/media/audio_input_sync_writer.cc
@@ -9,6 +9,7 @@
 #include "base/format_macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
+#include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/public/browser/browser_thread.h"
@@ -119,6 +120,7 @@ void AudioInputSyncWriter::Write(const AudioBus* data,
                                  double volume,
                                  bool key_pressed,
                                  uint32_t hardware_delay_bytes) {
+  TRACE_EVENT0("audio", "AudioInputSyncWriter::Write");
   ++write_count_;
   CheckTimeSinceLastWrite();
 
@@ -171,6 +173,8 @@ void AudioInputSyncWriter::Write(const AudioBus* data,
   if (write_error) {
     ++write_error_count_;
     ++trailing_write_error_count_;
+    TRACE_EVENT_INSTANT0("audio", "AudioInputSyncWriter write error",
+                         TRACE_EVENT_SCOPE_THREAD);
   } else {
     trailing_write_error_count_ = 0;
   }
@@ -330,6 +334,9 @@ bool AudioInputSyncWriter::SignalDataWrittenAndUpdateCounters() {
     const std::string error_message = "AISW: No room in socket buffer.";
     LOG(WARNING) << error_message;
     AddToNativeLog(error_message);
+    TRACE_EVENT_INSTANT0("audio",
+                         "AudioInputSyncWriter: No room in socket buffer",
+                         TRACE_EVENT_SCOPE_THREAD);
     return false;
   }