Added initial set of logging for AudioOutputController.

content/browser/renderer_host/media/audio_output_delegate_impl.cc

Index: content/browser/renderer_host/media/audio_output_delegate_impl.cc
diff --git a/content/browser/renderer_host/media/audio_output_delegate_impl.cc b/content/browser/renderer_host/media/audio_output_delegate_impl.cc
index 3625fcbfefaaa18f1dabe65e3af7eabbc3175f99..ebe6826772ce6526d47a814311a2491dab5cac26 100644
--- a/content/browser/renderer_host/media/audio_output_delegate_impl.cc
+++ b/content/browser/renderer_host/media/audio_output_delegate_impl.cc
@@ -12,6 +12,7 @@
 #include "content/browser/media/capture/audio_mirroring_manager.h"
 #include "content/browser/media/media_internals.h"
 #include "content/browser/renderer_host/media/audio_sync_reader.h"
+#include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/media_observer.h"
 #include "media/audio/audio_output_controller.h"
@@ -34,12 +35,15 @@ class AudioOutputDelegateImpl::ControllerEventHandler
   void OnControllerPaused() override;
   void OnControllerError() override;
 
+  void OnLog(const std::string& message) override;
+
   base::WeakPtr<AudioOutputDelegateImpl> delegate_;
+  int stream_id_;  // Retained separately for logging.
 };
 
 AudioOutputDelegateImpl::ControllerEventHandler::ControllerEventHandler(
     base::WeakPtr<AudioOutputDelegateImpl> delegate)
-    : delegate_(std::move(delegate)) {}
+    : delegate_(std::move(delegate)), stream_id_(delegate_->stream_id_) {}
 
 void AudioOutputDelegateImpl::ControllerEventHandler::OnControllerCreated() {
   BrowserThread::PostTask(
@@ -68,6 +72,13 @@ void AudioOutputDelegateImpl::ControllerEventHandler::OnControllerError() {
       base::BindOnce(&AudioOutputDelegateImpl::OnError, delegate_));
 }
 
+void AudioOutputDelegateImpl::ControllerEventHandler::OnLog(
+    const std::string& message) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&AudioOutputDelegateImpl::DoLog, stream_id_, message));

[Max Morin, 2017/05/29 14:25:44]

I just realized this should be BindOnce, like in all the other methods here.

[ossu-chromium, 2017/05/29 14:35:48]

I think I've been a bit hazy on the significance of Bind vs. BindOnce. I guess
that since each of these tasks will only be called once, BindOnce is the proper
one? Will fix!

[Max Morin, 2017/05/29 14:44:44]

Yes, it's a sort of documentation (with added efficiency bonus; since
OnceCallback is move-only, we don't have to reference count its internal state).
There are also some other neat things, like if you move something into the
BindOnce call, it will be moved out when the callback is called.

Basically, use BindOnce/OnceCallback when the callback should only be called
once, if that compiles.

+}
+
 std::unique_ptr<media::AudioOutputDelegate> AudioOutputDelegateImpl::Create(
     EventHandler* handler,
     media::AudioManager* audio_manager,
@@ -221,6 +232,15 @@ void AudioOutputDelegateImpl::OnError() {
   subscriber_->OnStreamError(stream_id_);
 }
 

[liberato (no reviews please), 2017/05/30 16:53:34]

please add "// static".

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

See comment in audio_output_delegate_impl.h.

+void AudioOutputDelegateImpl::DoLog(int stream_id, const std::string& msg) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  std::ostringstream oss;
+  oss << "[stream_id=" << stream_id << "] " << msg;
+  const std::string message = oss.str();
+  content::MediaStreamManager::SendMessageToNativeLog(message);
+  DVLOG(1) << message;
+}
+
 media::AudioOutputController* AudioOutputDelegateImpl::GetControllerForTesting()
     const {
   return controller_.get();