Allow AudioRendererMixerInput::Stop() to be called anytime.

BUG=157710
TEST=new unittest

Review URL: https://codereview.chromium.org/11270025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@164373 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 36 insertions, 10 deletions

diff --git a/media/base/audio_renderer_mixer_input.cc b/media/base/audio_renderer_mixer_input.cc
index b5756d2..c748f8f 100644
--- a/media/base/audio_renderer_mixer_input.cc
+++ b/media/base/audio_renderer_mixer_input.cc
@@ -13,6 +13,7 @@ AudioRendererMixerInput::AudioRendererMixerInput(
     const GetMixerCB& get_mixer_cb, const RemoveMixerCB& remove_mixer_cb)
     : playing_(false),
       initialized_(false),
+      started_(false),
       volume_(1.0f),
       get_mixer_cb_(get_mixer_cb),
       remove_mixer_cb_(remove_mixer_cb),
@@ -38,20 +39,29 @@ void AudioRendererMixerInput::Initialize(
 
 void AudioRendererMixerInput::Start() {
   DCHECK(initialized_);
+  DCHECK(!started_);
   mixer_->AddMixerInput(this);
+  started_ = true;
 }
 
 void AudioRendererMixerInput::Stop() {
-  DCHECK(initialized_);
+  // Stop() may be called at any time, so we can't blindly remove our input.
+  if (started_) {
+    mixer_->RemoveMixerInput(this);
+    started_ = false;
+  }
   playing_ = false;
-  mixer_->RemoveMixerInput(this);
 }
 
 void AudioRendererMixerInput::Play() {
+  DCHECK(initialized_);
+  DCHECK(started_);
   playing_ = true;
 }
 
 void AudioRendererMixerInput::Pause(bool /* flush */) {
+  DCHECK(initialized_);
+  DCHECK(started_);
   // We don't care about flush since Pause() simply indicates we should send
   // silence to AudioRendererMixer.
   playing_ = false;
diff --git a/media/base/audio_renderer_mixer_input.h b/media/base/audio_renderer_mixer_input.h
index dee7f3d..486f5c2 100644
--- a/media/base/audio_renderer_mixer_input.h
+++ b/media/base/audio_renderer_mixer_input.h
@@ -44,6 +44,7 @@ class MEDIA_EXPORT AudioRendererMixerInput
  private:
   bool playing_;
   bool initialized_;
+  bool started_;
   double volume_;
 
   // Callbacks provided during construction which allow AudioRendererMixerInput
diff --git a/media/base/audio_renderer_mixer_input_unittest.cc b/media/base/audio_renderer_mixer_input_unittest.cc
index 48b2232..a3cb3bc 100644
--- a/media/base/audio_renderer_mixer_input_unittest.cc
+++ b/media/base/audio_renderer_mixer_input_unittest.cc
@@ -25,14 +25,18 @@ class AudioRendererMixerInputTest : public testing::Test {
         AudioParameters::AUDIO_PCM_LINEAR, kChannelLayout, kSampleRate,
         kBitsPerChannel, kBufferSize);
 
+    CreateMixerInput();
+    fake_callback_.reset(new FakeAudioRenderCallback(0));
+    mixer_input_->Initialize(audio_parameters_, fake_callback_.get());
+    EXPECT_CALL(*this, RemoveMixer(testing::_));
+  }
+
+  void CreateMixerInput() {
     mixer_input_ = new AudioRendererMixerInput(
         base::Bind(
             &AudioRendererMixerInputTest::GetMixer, base::Unretained(this)),
         base::Bind(
             &AudioRendererMixerInputTest::RemoveMixer, base::Unretained(this)));
-    fake_callback_.reset(new FakeAudioRenderCallback(0));
-    mixer_input_->Initialize(audio_parameters_, fake_callback_.get());
-    EXPECT_CALL(*this, RemoveMixer(testing::_));
   }
 
   AudioRendererMixer* GetMixer(const AudioParameters& params) {
@@ -94,4 +98,14 @@ TEST_F(AudioRendererMixerInputTest, StartPlayPauseStopPlaying) {
   EXPECT_FALSE(mixer_input_->playing());
 }
 
+// Test that Stop() can be called before Initialize() and Start().
+TEST_F(AudioRendererMixerInputTest, StopBeforeInitializeOrStart) {
+  // |mixer_input_| was initialized during construction.
+  mixer_input_->Stop();
+
+  // Verify Stop() works without Initialize() or Start().
+  CreateMixerInput();
+  mixer_input_->Stop();
+}
+
 }  // namespace media
diff --git a/media/base/audio_renderer_mixer_unittest.cc b/media/base/audio_renderer_mixer_unittest.cc
index 0bc5516..aad2313 100644
--- a/media/base/audio_renderer_mixer_unittest.cc
+++ b/media/base/audio_renderer_mixer_unittest.cc
@@ -164,7 +164,7 @@ class AudioRendererMixerTest
     EXPECT_TRUE(RenderAndValidateAudioData(0.0f));
 
     // Start() all even numbered mixer inputs and ensure we still get silence.
-    for (size_t i = 0; i < mixer_inputs_.size(); ++i)
+    for (size_t i = 0; i < mixer_inputs_.size(); i += 2)
       mixer_inputs_[i]->Start();
     FillAudioData(1.0f);
     EXPECT_TRUE(RenderAndValidateAudioData(0.0f));
diff --git a/media/filters/audio_renderer_impl.cc b/media/filters/audio_renderer_impl.cc
index 772af20..2805ed0 100644
--- a/media/filters/audio_renderer_impl.cc
+++ b/media/filters/audio_renderer_impl.cc
@@ -86,12 +86,13 @@ void AudioRendererImpl::Flush(const base::Closure& callback) {
 void AudioRendererImpl::Stop(const base::Closure& callback) {
   DCHECK(!callback.is_null());
 
-  if (!stopped_) {
-    sink_->Stop();
-    stopped_ = true;
-  }
   {
     base::AutoLock auto_lock(lock_);
+    if (!stopped_) {
+      sink_->Stop();
+      stopped_ = true;
+    }
+
     state_ = kStopped;
     algorithm_.reset(NULL);
     init_cb_.Reset();