[Chromecast] Initialize media_resource_tracker with media_thread.

chromecast/browser/cast_browser_main_parts.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromecast/browser/cast_browser_main_parts.h"
 
 #include <stddef.h>
 #include <string.h>
 
 #include <string>
@@ skipping 299 matching lines @@
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 CastBrowserMainParts::GetMediaTaskRunner() {
 #if BUILDFLAG(IS_CAST_USING_CMA_BACKEND)
   if (!media_thread_) {
     media_thread_.reset(new base::Thread("CastMediaThread"));
     base::Thread::Options options;
     options.priority = base::ThreadPriority::REALTIME_AUDIO;
     CHECK(media_thread_->StartWithOptions(options));
+    // Start the media_resource_tracker as soon as the media thread is created.
+    // There are services that run on the media thread that depend on it,
+    // and we want to initialize it with the correct task runner before any
+    // tasks that might use it are posted to the media thread.
+    media_resource_tracker_ = new media::MediaResourceTracker(
+        base::ThreadTaskRunnerHandle::Get(), media_thread_->task_runner());
   }
   return media_thread_->task_runner();
 #else
   return nullptr;
 #endif  // BUILDFLAG(IS_CAST_USING_CMA_BACKEND)
 }
 
 #if BUILDFLAG(IS_CAST_USING_CMA_BACKEND)
 media::MediaResourceTracker* CastBrowserMainParts::media_resource_tracker() {
-  if (!media_resource_tracker_) {
-    media_resource_tracker_ = new media::MediaResourceTracker(
-        base::ThreadTaskRunnerHandle::Get(), GetMediaTaskRunner());
-  }
+  DCHECK(media_thread_);
   return media_resource_tracker_;
 }
 
 media::MediaPipelineBackendManager*
 CastBrowserMainParts::media_pipeline_backend_manager() {
   if (!media_pipeline_backend_manager_) {
     media_pipeline_backend_manager_.reset(
         new media::MediaPipelineBackendManager(GetMediaTaskRunner()));
   }
   return media_pipeline_backend_manager_.get();
@@ skipping 218 matching lines @@
 
 void CastBrowserMainParts::PostDestroyThreads() {
 #if !defined(OS_ANDROID)
   media_resource_tracker_->FinalizeAndDestroy();
   media_resource_tracker_ = nullptr;
 #endif
 }
 
 }  // namespace shell
 }  // namespace chromecast