cc: Cleanup class/struct forward declarations

cc/test/fake_layer_tree_host_impl.h

 // Copyright 2012 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_TEST_FAKE_LAYER_TREE_HOST_IMPL_H_
 #define CC_TEST_FAKE_LAYER_TREE_HOST_IMPL_H_
 
 #include "cc/test/fake_layer_tree_host_impl_client.h"
 #include "cc/test/fake_rendering_stats_instrumentation.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/single_thread_proxy.h"
 
-namespace gpu {
-class GpuMemoryBufferManager;
-}
-
 namespace cc {
 
 class AnimationHost;
 
 class FakeLayerTreeHostImpl : public LayerTreeHostImpl {
  public:
   FakeLayerTreeHostImpl(TaskRunnerProvider* task_runner_provider,
                         TaskGraphRunner* task_graph_runner);
   FakeLayerTreeHostImpl(const LayerTreeSettings& settings,
                         TaskRunnerProvider* task_runner_provider,
@@ skipping 34 matching lines @@
 
  private:
   FakeLayerTreeHostImplClient client_;
   FakeRenderingStatsInstrumentation stats_instrumentation_;
   bool notify_tile_state_changed_called_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_FAKE_LAYER_TREE_HOST_IMPL_H_