Plumb audio focus support for spitzer clients.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index ad9ca1d450ca82be4fe7db0f33a072d7d444d7c3..f09ca270ce59482be07c60b20a7e9dda6b429c7b 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -20,6 +20,7 @@
 #include "content/browser/media/audio_stream_monitor.h"
 #include "content/browser/media/capture/audio_mirroring_manager.h"
 #include "content/browser/media/media_internals.h"
+#include "content/browser/media/media_web_contents_observer.h"
 #include "content/browser/renderer_host/media/audio_input_device_manager.h"
 #include "content/browser/renderer_host/media/audio_sync_reader.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
@@ -159,6 +160,8 @@ class AudioRendererHost::AudioEntry
 
   bool playing() const { return playing_; }
   void set_playing(bool playing) { playing_ = playing; }
+  void update_last_pause_time() { last_pause_time_ = base::TimeTicks::Now(); }
+  base::TimeTicks last_pause_time() { return last_pause_time_; }
 
  private:
   // media::AudioOutputController::EventHandler implementation.
@@ -183,6 +186,8 @@ class AudioRendererHost::AudioEntry
   const scoped_refptr<media::AudioOutputController> controller_;
 
   bool playing_;
+
+  base::TimeTicks last_pause_time_;
 };
 
 AudioRendererHost::AudioEntry::AudioEntry(
@@ -614,6 +619,30 @@ void AudioRendererHost::OnPlayStream(int stream_id) {
     return;
   }
 
+  if (entry->controller()->GetAudioParameters().effects() &
+      media::AudioParameters::FOCUSABLE) {
+    MediaWebContentsObserver::WaitForAudioFocusAsync(
+        render_process_id_, entry->render_frame_id(),
+        base::Bind(&AudioRendererHost::OnFocusAvailable, this, stream_id,
+                   base::TimeTicks::Now()));
+  } else {
+    entry->controller()->Play();
+    audio_log_->OnStarted(stream_id);
+  }
+}
+
+void AudioRendererHost::OnFocusAvailable(int stream_id,
+                                         base::TimeTicks play_time) {
+  // Abort the playback if:
+  //   - The entry has been destroyed while focus was requested.
+  //   - A subsequent pause has come through.
+  //
+  // A focus request never fails via this path. If it's denied a pause request
+  // will be issues directly to the player.
+  AudioEntry* entry = LookupById(stream_id);
+  if (!entry || play_time < entry->last_pause_time())
+    return;
+
   entry->controller()->Play();
   audio_log_->OnStarted(stream_id);
 }
@@ -627,6 +656,7 @@ void AudioRendererHost::OnPauseStream(int stream_id) {
     return;
   }
 
+  entry->update_last_pause_time();
   entry->controller()->Pause();
   audio_log_->OnStopped(stream_id);
 }