Guarantee PPAPI Audio playbacks are stopped in Pause().

BUG=none
TEST=pepper audio demo is playing audio

Review URL: http://codereview.chromium.org/3142005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@58014 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 51 insertions, 11 deletions

diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index 27938f9..45ad62c 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -13,6 +13,8 @@ static const uint32 kMaxHardwareBufferSize = 2 * kMegabytes;
 static const int kMaxChannels = 32;
 static const int kMaxBitsPerSample = 64;
 static const int kMaxSampleRate = 192000;
+// Signal a pause in low-latency mode.
+static const int kPauseMark = -1;
 
 // Return true if the parameters for creating an audio stream is valid.
 // Return false otherwise.
@@ -239,6 +241,11 @@ void AudioOutputController::DoPause() {
   // TODO(hclam): Actually pause the audio device.
   stream_->Stop();
 
+  if (LowLatencyMode()) {
+    // Send a special pause mark to the low-latency audio thread.
+    sync_reader_->UpdatePendingBytes(kPauseMark);
+  }
+
   handler_->OnPaused(this);
 }
 
diff --git a/webkit/glue/plugins/pepper_audio.cc b/webkit/glue/plugins/pepper_audio.cc
index 98edb22..3babc2f 100644
--- a/webkit/glue/plugins/pepper_audio.cc
+++ b/webkit/glue/plugins/pepper_audio.cc
@@ -113,6 +113,7 @@ AudioConfig* AudioConfig::AsAudioConfig() {
 
 Audio::Audio(PluginModule* module)
     : Resource(module),
+      playing_(false),
       socket_(NULL),
       shared_memory_(NULL),
       shared_memory_size_(0),
@@ -160,6 +161,35 @@ bool Audio::Init(PluginDelegate* plugin_delegate, PP_Resource config_id,
   return audio_.get() != NULL;
 }
 
+bool Audio::StartPlayback() {
+  if (playing_)
+    return true;
+
+  CHECK(!audio_thread_.get());
+  if (callback_ && socket_.get()) {
+    audio_thread_.reset(new base::DelegateSimpleThread(this,
+                                                       "plugin_audio_thread"));
+    audio_thread_->Start();
+  }
+  playing_ = true;
+  return audio_->StartPlayback();
+}
+
+bool Audio::StopPlayback() {
+  if (!playing_)
+    return true;
+
+  if (!audio_->StopPlayback())
+    return false;
+
+  if (audio_thread_.get()) {
+    audio_thread_->Join();
+    audio_thread_.reset();
+  }
+  playing_ = false;
+  return true;
+}
+
 void Audio::StreamCreated(base::SharedMemoryHandle shared_memory_handle,
                           size_t shared_memory_size,
                           base::SyncSocket::Handle socket_handle) {
@@ -169,9 +199,12 @@ void Audio::StreamCreated(base::SharedMemoryHandle shared_memory_handle,
 
   if (callback_) {
     shared_memory_->Map(shared_memory_size_);
-    audio_thread_.reset(new base::DelegateSimpleThread(this,
-                                                       "plugin_audio_thread"));
-    audio_thread_->Start();
+    // In common case StartPlayback() was called before StreamCreated().
+    if (playing_) {
+      audio_thread_.reset(new base::DelegateSimpleThread(this,
+          "plugin_audio_thread"));
+      audio_thread_->Start();
+    }
   }
 }
 
@@ -182,6 +215,9 @@ void Audio::Run() {
   while (sizeof(pending_data) ==
       socket_->Receive(&pending_data, sizeof(pending_data)) &&
       pending_data >= 0) {
+    // Exit the thread on pause.
+    if (pending_data < 0)
+      return;
     callback_(buffer, user_data_);
   }
 }
diff --git a/webkit/glue/plugins/pepper_audio.h b/webkit/glue/plugins/pepper_audio.h
index d6a175b..d9a9e86 100644
--- a/webkit/glue/plugins/pepper_audio.h
+++ b/webkit/glue/plugins/pepper_audio.h
@@ -58,15 +58,9 @@ class Audio : public Resource,
     return config_->GetReference();
   }
 
-  bool StartPlayback() {
-    // TODO(neb): Make this synchronous.
-    return audio_->StartPlayback();
-  }
+  bool StartPlayback();
 
-  bool StopPlayback() {
-    // TODO(neb): Make this synchronous.
-    return audio_->StopPlayback();
-  }
+  bool StopPlayback();
 
   // Resource override.
   virtual Audio* AsAudio();
@@ -82,6 +76,9 @@ class Audio : public Resource,
   virtual void Run();
   // End of DelegateSimpleThread::Delegate implementation.
 
+  // True if playing the stream.
+  bool playing_;
+
   // AudioConfig used for creating this Audio object.
   scoped_refptr<AudioConfig> config_;