Reland: Add Stop() to AudioDecoder. (https://codereview.chromium.org/126793002/)

media/filters/audio_renderer_impl.cc

Index: media/filters/audio_renderer_impl.cc
diff --git a/media/filters/audio_renderer_impl.cc b/media/filters/audio_renderer_impl.cc
index 9ade30dc0dc6fdbba1dae9d7e8cbd041aee6638e..76d9e76b6885a1ac97c66e4307ca48931211aad2 100644
--- a/media/filters/audio_renderer_impl.cc
+++ b/media/filters/audio_renderer_impl.cc
@@ -147,8 +147,8 @@ void AudioRendererImpl::DoFlush_Locked() {
   DCHECK_EQ(state_, kPaused);
 
   if (decrypting_demuxer_stream_) {
-    decrypting_demuxer_stream_->Reset(BindToCurrentLoop(
-        base::Bind(&AudioRendererImpl::ResetDecoder, weak_this_)));
+    decrypting_demuxer_stream_->Reset(
+        base::Bind(&AudioRendererImpl::ResetDecoder, weak_this_));
     return;
   }
 
@@ -157,28 +157,29 @@ void AudioRendererImpl::DoFlush_Locked() {
 
 void AudioRendererImpl::ResetDecoder() {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  decoder_->Reset(BindToCurrentLoop(
-      base::Bind(&AudioRendererImpl::ResetDecoderDone, weak_this_)));
+  decoder_->Reset(base::Bind(&AudioRendererImpl::ResetDecoderDone, weak_this_));
 }
 
 void AudioRendererImpl::ResetDecoderDone() {
-  base::AutoLock auto_lock(lock_);
-  if (state_ == kStopped)
-    return;
-
-  DCHECK_EQ(state_, kPaused);
-  DCHECK(!flush_cb_.is_null());
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  {
+    base::AutoLock auto_lock(lock_);
+    if (state_ == kStopped)
+      return;
 
-  audio_time_buffered_ = kNoTimestamp();
-  current_time_ = kNoTimestamp();
-  received_end_of_stream_ = false;
-  rendered_end_of_stream_ = false;
-  preroll_aborted_ = false;
+    DCHECK_EQ(state_, kPaused);
+    DCHECK(!flush_cb_.is_null());
 
-  earliest_end_time_ = now_cb_.Run();
-  splicer_->Reset();
-  algorithm_->FlushBuffers();
+    audio_time_buffered_ = kNoTimestamp();
+    current_time_ = kNoTimestamp();
+    received_end_of_stream_ = false;
+    rendered_end_of_stream_ = false;
+    preroll_aborted_ = false;
 
+    earliest_end_time_ = now_cb_.Run();
+    splicer_->Reset();
+    algorithm_->FlushBuffers();
+  }
   base::ResetAndReturn(&flush_cb_).Run();
 }
 
@@ -196,14 +197,32 @@ void AudioRendererImpl::Stop(const base::Closure& callback) {
 
   {
     base::AutoLock auto_lock(lock_);
+    if (state_ == kStopped)
+      return;
+
+    DCHECK(init_cb_.is_null());
+
     ChangeState_Locked(kStopped);
-    algorithm_.reset(NULL);
+    algorithm_.reset();
     init_cb_.Reset();
     underflow_cb_.Reset();
     time_cb_.Reset();
     flush_cb_.Reset();
   }
 
+  if (!init_cb_.is_null()) {

[rileya (GONE FROM CHROMIUM), 2014/01/21 19:08:50]

This resolves the layout test failure (if we have a pending |init_cb_| Abort the
decoder selector and dispatch an error to the cb).

+    decoder_selector_->Abort();
+    base::ResetAndReturn(&init_cb_).Run(PIPELINE_ERROR_ABORT);

[rileya (GONE FROM CHROMIUM), 2014/01/21 19:08:50]

Is there a better error for this?

[DaleCurtis, 2014/01/21 21:14:39]

Hmm, I don't see VideoFrameStream / VideoRendererImpl doing this, is that a bug
there or is this unnecessary?

+    callback.Run();
+    return;
+  }
+
+  if (decoder_) {
+    DCHECK(task_runner_->BelongsToCurrentThread());
+    decoder_->Stop(callback);

[rileya (GONE FROM CHROMIUM), 2014/01/21 19:08:50]

The canary crash was caused (so far as I can tell) by a race between
StopDecoderDone and AttemptRead, where we would post a Read() to |decoder_|
after Stop() had already been called on it, resulting in segfault-y fun when we
try to decode with a stopped decoder.

To solve this, I simply removed StopDecoderDone and the async call to it, as I
couldn't actually see any reason it was necessary (I'd originally included it to
match Reset/DecoderResetDone).

+    return;
+  }
+
   callback.Run();
 }