cc: Cleanup class/struct forward declarations

cc/trees/task_runner_provider.h

 // Copyright 2015 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 CC_TREES_TASK_RUNNER_PROVIDER_H_
 #define CC_TREES_TASK_RUNNER_PROVIDER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "cc/base/cc_export.h"
 
 namespace base {
-namespace trace_event {
-class TracedValue;
-}
 class SingleThreadTaskRunner;
 }
 
 namespace cc {
 class BlockingTaskRunner;
 
 // Class responsible for controlling access to the main and impl task runners.
 // Useful for assertion checks.
 class CC_EXPORT TaskRunnerProvider {
  public:
@@ skipping 74 matching lines @@
   ~DebugScopedSetMainThreadBlocked() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DebugScopedSetMainThreadBlocked);
 };
 #endif
 
 }  // namespace cc
 
 #endif  // CC_TREES_TASK_RUNNER_PROVIDER_H_