Pipeline: Use WeakPtr for DemuxerHost Calls and Tasks.

media/base/pipeline.cc

Index: media/base/pipeline.cc
diff --git a/media/base/pipeline.cc b/media/base/pipeline.cc
index 91ac2cfa139d4399957659ae9943771ed4d7a7e9..be2323e46314e822aa53ea9da7c7b6960d0382e8 100644
--- a/media/base/pipeline.cc
+++ b/media/base/pipeline.cc
@@ -269,16 +269,10 @@ Pipeline::State Pipeline::GetNextState() const {
   return state_;
 }
 
-// The use of base::Unretained(this) in the following 3 functions is safe
-// because these functions are called by the Demuxer directly, before the stop
-// callback is posted by the Demuxer. So the posted tasks will always be
-// executed before the stop callback is executed, and hence before the Pipeline
-// is destructed.
-
 void Pipeline::OnDemuxerError(PipelineStatus error) {
   task_runner_->PostTask(FROM_HERE,
                          base::Bind(&Pipeline::ErrorChangedTask,
-                                    base::Unretained(this),
+                                    weak_this_for_demuxer_,
                                     error));
 }
 
@@ -286,7 +280,7 @@ void Pipeline::AddTextStream(DemuxerStream* text_stream,
                              const TextTrackConfig& config) {
   task_runner_->PostTask(FROM_HERE,
                          base::Bind(&Pipeline::AddTextStreamTask,
-                                    base::Unretained(this),
+                                    weak_this_for_demuxer_,
                                     text_stream,
                                     config));
 }
@@ -294,7 +288,7 @@ void Pipeline::AddTextStream(DemuxerStream* text_stream,
 void Pipeline::RemoveTextStream(DemuxerStream* text_stream) {
   task_runner_->PostTask(FROM_HERE,
                          base::Bind(&Pipeline::RemoveTextStreamTask,
-                                    base::Unretained(this),
+                                    weak_this_for_demuxer_,
                                     text_stream));
 }
 
@@ -550,6 +544,10 @@ void Pipeline::OnStopCompleted(PipelineStatus status) {
   filter_collection_.reset();
   demuxer_ = NULL;
 
+  // Invalid all weak pointers so it's safe to destroy |this| on the render
+  // main thread.
+  weak_factory_.InvalidateWeakPtrs();
+
   // If we stop during initialization/seeking we want to run |seek_cb_|
   // followed by |stop_cb_| so we don't leave outstanding callbacks around.
   if (!seek_cb_.is_null()) {
@@ -779,6 +777,7 @@ void Pipeline::RemoveTextStreamTask(DemuxerStream* text_stream) {
 void Pipeline::InitializeDemuxer(const PipelineStatusCB& done_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
+  weak_this_for_demuxer_ = weak_factory_.GetWeakPtr();
   demuxer_ = filter_collection_->GetDemuxer();
   demuxer_->Initialize(this, done_cb, text_renderer_);
 }