Added initial set of logging for AudioOutputController.

media/audio/audio_output_controller.cc

Index: media/audio/audio_output_controller.cc
diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index 6c9daa0c00fac39375f51ecc5465becdb7cdb15a..fdca8112f14caba8fe3da63ef0d365914576dfd8 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -12,6 +12,7 @@
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/numerics/safe_conversions.h"
+#include "base/strings/stringprintf.h"
 #include "base/task_runner_util.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
@@ -107,6 +108,8 @@ void AudioOutputController::DoCreate(bool is_for_device_change) {
   DCHECK(message_loop_->BelongsToCurrentThread());
   SCOPED_UMA_HISTOGRAM_TIMER("Media.AudioOutputController.CreateTime");
   TRACE_EVENT0("audio", "AudioOutputController::DoCreate");
+  handler_->OnLog(base::StringPrintf("AOC::DoCreate (for device change: %s)",
+                                     is_for_device_change ? "yes" : "no"));
 
   // Close() can be called before DoCreate() is executed.
   if (state_ == kClosed)
@@ -151,6 +154,7 @@ void AudioOutputController::DoPlay() {
   DCHECK(message_loop_->BelongsToCurrentThread());
   SCOPED_UMA_HISTOGRAM_TIMER("Media.AudioOutputController.PlayTime");
   TRACE_EVENT0("audio", "AudioOutputController::DoPlay");
+  handler_->OnLog("AOC::DoPlay");
 
   // We can start from created or paused state.
   if (state_ != kCreated && state_ != kPaused)
@@ -201,6 +205,7 @@ void AudioOutputController::DoPause() {
   DCHECK(message_loop_->BelongsToCurrentThread());
   SCOPED_UMA_HISTOGRAM_TIMER("Media.AudioOutputController.PauseTime");
   TRACE_EVENT0("audio", "AudioOutputController::DoPause");
+  handler_->OnLog("AOC::DoPause");
 
   StopStream();
 
@@ -219,6 +224,7 @@ void AudioOutputController::DoClose() {
   DCHECK(message_loop_->BelongsToCurrentThread());
   SCOPED_UMA_HISTOGRAM_TIMER("Media.AudioOutputController.CloseTime");
   TRACE_EVENT0("audio", "AudioOutputController::DoClose");
+  handler_->OnLog("AOC::DoClose");
 
   if (state_ != kClosed) {
     DoStopCloseAndClearStream();
@@ -353,6 +359,27 @@ void AudioOutputController::OnDeviceChange() {
   SCOPED_UMA_HISTOGRAM_TIMER("Media.AudioOutputController.DeviceChangeTime");
   TRACE_EVENT0("audio", "AudioOutputController::OnDeviceChange");
 
+  auto state_to_string = [](State state) {
+    switch (state) {
+      case AudioOutputController::kEmpty:
+        return "empty";
+      case AudioOutputController::kCreated:
+        return "created";
+      case AudioOutputController::kPlaying:
+        return "playing";
+      case AudioOutputController::kPaused:
+        return "paused";
+      case AudioOutputController::kClosed:
+        return "closed";
+      case AudioOutputController::kError:
+        return "error";
+    };
+    return "unknown";

[liberato (no reviews please), 2017/05/30 16:53:35]

will it compile if one omits a case in the switch?  i don't think it will.

if not, then one can remove this.

[ossu-chromium, 2017/05/31 11:16:27]

It won't, but my thought is if state ever goes bad (i.e. OnDeviceChange getting
called after or during the destruction of an AudioOutputController), it's more
informative to have that be logged as "unknown" than to have a crash in
StringPrintf. Though, I may be wrong. Perhaps change it to something more
obvious, like "bad state".

+  };
+
+  handler_->OnLog(base::StringPrintf("AOC::OnDeviceChange while in state: %s",
+                                     state_to_string(state_)));
+
   // TODO(dalecurtis): Notify the renderer side that a device change has
   // occurred.  Currently querying the hardware information here will lead to
   // crashes on OSX.  See http://crbug.com/158170.