Pass in media message loop to VideoRendererBase and enforce calling on the right thread.

media/filters/video_renderer_base.cc

Index: media/filters/video_renderer_base.cc
diff --git a/media/filters/video_renderer_base.cc b/media/filters/video_renderer_base.cc
index 8f6bf8a3d0254dc82578f0fb4a5f7b20f1a7f029..07c0141bf71c740076237e34d953d62d85ffd01b 100644
--- a/media/filters/video_renderer_base.cc
+++ b/media/filters/video_renderer_base.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
+#include "base/message_loop.h"
 #include "base/threading/platform_thread.h"
 #include "media/base/buffers.h"
 #include "media/base/limits.h"
@@ -19,9 +20,11 @@ base::TimeDelta VideoRendererBase::kMaxLastFrameDuration() {
   return base::TimeDelta::FromMilliseconds(250);
 }
 
-VideoRendererBase::VideoRendererBase(const base::Closure& paint_cb,
-                                     const SetOpaqueCB& set_opaque_cb,
-                                     bool drop_frames)
+VideoRendererBase::VideoRendererBase(
+    const base::Closure& paint_cb,
+    const SetOpaqueCB& set_opaque_cb,
+    bool drop_frames,
+    const scoped_refptr<base::MessageLoopProxy>& message_loop)
     : frame_available_(&lock_),
       state_(kUninitialized),
       thread_(base::kNullThreadHandle),
@@ -31,7 +34,8 @@ VideoRendererBase::VideoRendererBase(const base::Closure& paint_cb,
       drop_frames_(drop_frames),
       playback_rate_(0),
       paint_cb_(paint_cb),
-      set_opaque_cb_(set_opaque_cb) {
+      set_opaque_cb_(set_opaque_cb),
+      decoder_message_loop_(message_loop) {

[Ami GONE FROM CHROMIUM, 2012/11/29 23:34:23]

Could DCHECK that this is *not* the current loop, for sanity.

   DCHECK(!paint_cb_.is_null());
 }
 
@@ -55,11 +59,9 @@ void VideoRendererBase::Flush(const base::Closure& callback) {
   flush_cb_ = callback;
   state_ = kFlushingDecoder;
 
-  // We must unlock here because the callback might run within the Flush()
-  // call.
-  // TODO: Remove this line when fixing http://crbug.com/125020
-  base::AutoUnlock auto_unlock(lock_);
-  decoder_->Reset(base::Bind(&VideoRendererBase::OnDecoderFlushDone, this));
+  decoder_message_loop_->PostTask(FROM_HERE, base::Bind(
+      &VideoDecoder::Reset, decoder_, base::Bind(
+      &VideoRendererBase::OnDecoderFlushDone, this)));
 }
 
 void VideoRendererBase::Stop(const base::Closure& callback) {
@@ -90,7 +92,8 @@ void VideoRendererBase::Stop(const base::Closure& callback) {
   if (thread_to_join != base::kNullThreadHandle)
     base::PlatformThread::Join(thread_to_join);
 
-  decoder_->Stop(callback);
+  decoder_message_loop_->PostTask(FROM_HERE, base::Bind(
+      &VideoDecoder::Stop, decoder_, callback));
 }
 
 void VideoRendererBase::SetPlaybackRate(float playback_rate) {
@@ -195,6 +198,7 @@ void VideoRendererBase::OnDecoderInitDone(
   // have not populated any buffers yet.
   state_ = kFlushed;
 
+  // XXX we're taking advantage of the fact this is already on the right thread
   set_opaque_cb_.Run(!decoder_->HasAlpha());
   set_opaque_cb_.Reset();
 
@@ -571,7 +575,9 @@ void VideoRendererBase::AttemptRead_Locked() {
   }
 
   pending_read_ = true;
-  decoder_->Read(base::Bind(&VideoRendererBase::FrameReady, this));
+  decoder_message_loop_->PostTask(FROM_HERE, base::Bind(
+      &VideoDecoder::Read, decoder_, base::Bind(
+      &VideoRendererBase::FrameReady, this)));
 }
 
 void VideoRendererBase::OnDecoderFlushDone() {