compositor worker: Use a WebThread for the compositor thread.

content/child/blink_platform_impl.h

 // 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.
 
 #ifndef CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 #define CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 173 matching lines @@
 
   blink::WebString domCodeStringFromEnum(int dom_code) override;
   int domEnumFromCodeString(const blink::WebString& codeString) override;
   blink::WebString domKeyStringFromEnum(int dom_key) override;
   int domKeyEnumFromString(const blink::WebString& key_string) override;
 
   scoped_ptr<scheduler::WebThreadBase> createThreadWithOptions(
       const char* name,
       base::Thread::Options);
 
-  // This class does *not* own |compositor_thread|. It is the responsibility of
-  // the caller to ensure that the compositor thread is cleared before it is
+  // This class does *not* own the compositor thread. It is the responsibility
+  // of the caller to ensure that the compositor thread is cleared before it is
   // destructed.
-  void set_compositor_thread(scheduler::WebThreadBase* compositor_thread) {
-    compositor_thread_ = compositor_thread;
-  }
+  scoped_ptr<scheduler::WebThreadBase> createCompositorThread();
+  void reset_compositor_thread() { compositor_thread_ = nullptr; }
 
  private:
   void InternalInit();
+  void WaitUntilWebThreadTLSUpdate(scheduler::WebThreadBase* thread);
   void UpdateWebThreadTLS(blink::WebThread* thread, base::WaitableEvent* event);
 
   bool IsMainThread() const;
 
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
   WebThemeEngineImpl native_theme_engine_;
   WebFallbackThemeEngineImpl fallback_theme_engine_;
   base::ThreadLocalStorage::Slot current_thread_slot_;
   webcrypto::WebCryptoImpl web_crypto_;
   scoped_ptr<WebGeofencingProviderImpl> geofencing_provider_;
   base::ScopedPtrHashMap<blink::WebMemoryDumpProvider*,
                          scoped_ptr<WebMemoryDumpProviderAdapter>>
       memory_dump_providers_;
   base::ScopedPtrHashMap<blink::Platform::TraceLogEnabledStateObserver*,
                          scoped_ptr<TraceLogObserverAdapter>>
       trace_log_observers_;
 
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
   scoped_refptr<NotificationDispatcher> notification_dispatcher_;
   scoped_refptr<PushDispatcher> push_dispatcher_;
   scoped_ptr<PermissionDispatcher> permission_client_;
   scoped_ptr<BackgroundSyncProvider> main_thread_sync_provider_;
 
   scheduler::WebThreadBase* compositor_thread_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_BLINK_PLATFORM_IMPL_H_