Allow media track switching.

media/renderers/default_renderer_factory.cc

Index: media/renderers/default_renderer_factory.cc
diff --git a/media/renderers/default_renderer_factory.cc b/media/renderers/default_renderer_factory.cc
index 5d1eb00e8184072cf3bbcdf9e45888c0be055bb7..9bf6b6ee6a13dbb4e32afdad7c3caab429f39e49 100644
--- a/media/renderers/default_renderer_factory.cc
+++ b/media/renderers/default_renderer_factory.cc
@@ -104,7 +104,15 @@ std::unique_ptr<Renderer> DefaultRendererFactory::CreateRenderer(
 
   std::unique_ptr<AudioRenderer> audio_renderer(new AudioRendererImpl(
       media_task_runner, audio_renderer_sink,
-      CreateAudioDecoders(media_task_runner), media_log_));
+      // Unretained is safe here, because the RendererFactory is guaranteed to
+      // outlive the RendererImpl. The RendererImpl is destroyed when WMPI
+      // destructor calls pipeline_controller_.Stop() -> PipelineImpl::Stop() ->
+      // RendererWrapper::Stop -> RendererWrapper::DestroyRenderer(). And the
+      // RendererFactory is owned by WMPI and gets called after WMPI destructor
+      // finishes.
+      base::Bind(&DefaultRendererFactory::CreateAudioDecoders,
+                 base::Unretained(this), media_task_runner),
+      media_log_));
 
   GpuVideoAcceleratorFactories* gpu_factories = nullptr;
   if (!get_gpu_factories_cb_.is_null())
@@ -112,7 +120,15 @@ std::unique_ptr<Renderer> DefaultRendererFactory::CreateRenderer(
 
   std::unique_ptr<VideoRenderer> video_renderer(new VideoRendererImpl(
       media_task_runner, worker_task_runner, video_renderer_sink,
-      CreateVideoDecoders(media_task_runner, request_surface_cb, gpu_factories),
+      // Unretained is safe here, because the RendererFactory is guaranteed to
+      // outlive the RendererImpl. The RendererImpl is destroyed when WMPI
+      // destructor calls pipeline_controller_.Stop() -> PipelineImpl::Stop() ->
+      // RendererWrapper::Stop -> RendererWrapper::DestroyRenderer(). And the
+      // RendererFactory is owned by WMPI and gets called after WMPI destructor
+      // finishes.
+      base::Bind(&DefaultRendererFactory::CreateVideoDecoders,
+                 base::Unretained(this), media_task_runner, request_surface_cb,
+                 gpu_factories),
       true, gpu_factories, media_log_));
 
   return base::MakeUnique<RendererImpl>(