Fix dropped Play event when there's a pending pause.

If the message queue is built in such a way that DoPlay()->DoPause()->DoPlay()
ends up executing before the the first DoPlay()'s PollAndStartIfDataReady() runs,
we'll end up dropping the play and keeping the pause.

Fixed by ensuring we drop the pause if we receive a play before the pause is
consumed by PollAndStartIfDataReady().

BUG=111272
TEST=unittests, test.html test case in bug. Manual seeking in buffered areas.

Review URL: https://chromiumcodereview.appspot.com/10386037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@136162 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 55 insertions, 2 deletions

diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index cdaca79..da90f10 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -148,8 +148,13 @@ void AudioOutputController::DoPlay() {
   DCHECK(message_loop_->BelongsToCurrentThread());
 
   // We can start from created or paused state.
-  if (state_ != kCreated && state_ != kPaused)
+  if (state_ != kCreated && state_ != kPaused) {
+    // If a pause is pending drop it.  Otherwise the controller might hang since
+    // the corresponding play event has already occurred.
+    if (state_ == kPausedWhenStarting)
+      state_ = kStarting;
     return;
+  }
 
   state_ = kStarting;
 
diff --git a/media/audio/audio_output_controller_unittest.cc b/media/audio/audio_output_controller_unittest.cc
index 05f3d7f..f40a9ae 100644
--- a/media/audio/audio_output_controller_unittest.cc
+++ b/media/audio/audio_output_controller_unittest.cc
@@ -153,7 +153,6 @@ TEST_F(AudioOutputControllerTest, PlayPauseClose) {
   CloseAudioController(controller);
 }
 
-
 TEST_F(AudioOutputControllerTest, HardwareBufferTooLarge) {
   scoped_ptr<AudioManager> audio_manager(AudioManager::Create());
   if (!audio_manager->HasAudioOutputDevices())
@@ -175,4 +174,53 @@ TEST_F(AudioOutputControllerTest, HardwareBufferTooLarge) {
   ASSERT_FALSE(controller);
 }
 
+TEST_F(AudioOutputControllerTest, PlayPausePlayClose) {
+  scoped_ptr<AudioManager> audio_manager(AudioManager::Create());
+  if (!audio_manager->HasAudioOutputDevices())
+    return;
+
+  MockAudioOutputControllerEventHandler event_handler;
+  base::WaitableEvent event(false, false);
+  EXPECT_CALL(event_handler, OnCreated(NotNull()))
+      .WillOnce(InvokeWithoutArgs(&event, &base::WaitableEvent::Signal));
+
+  // OnPlaying() will be called only once.
+  base::WaitableEvent play_event(false, false);
+  EXPECT_CALL(event_handler, OnPlaying(NotNull()))
+      .WillOnce(InvokeWithoutArgs(&play_event, &base::WaitableEvent::Signal));
+
+  // OnPaused() should never be called since the pause during kStarting is
+  // dropped when the second play comes in.
+  EXPECT_CALL(event_handler, OnPaused(NotNull()))
+      .Times(0);
+
+  MockAudioOutputControllerSyncReader sync_reader;
+  EXPECT_CALL(sync_reader, UpdatePendingBytes(_))
+      .Times(AtLeast(2));
+  EXPECT_CALL(sync_reader, Read(_, kHardwareBufferSize))
+      .WillRepeatedly(DoAll(SignalEvent(&event), Return(4)));
+  EXPECT_CALL(sync_reader, DataReady())
+      .WillRepeatedly(Return(true));
+  EXPECT_CALL(sync_reader, Close());
+
+  AudioParameters params(AudioParameters::AUDIO_PCM_LINEAR, kChannelLayout,
+                         kSampleRate, kBitsPerSample, kSamplesPerPacket);
+  scoped_refptr<AudioOutputController> controller =
+      AudioOutputController::Create(
+          audio_manager.get(), &event_handler, params, &sync_reader);
+  ASSERT_TRUE(controller.get());
+
+  // Wait for OnCreated() to be called.
+  event.Wait();
+
+  ASSERT_FALSE(play_event.IsSignaled());
+  controller->Play();
+  controller->Pause();
+  controller->Play();
+  play_event.Wait();
+
+  // Now stop the controller.
+  CloseAudioController(controller);
+}
+
 }  // namespace media