Remove parts of //cc we aren't using

cc/trees/layer_tree_host_single_thread_client.h

-// Copyright 2013 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_LAYER_TREE_HOST_SINGLE_THREAD_CLIENT_H_
-#define CC_TREES_LAYER_TREE_HOST_SINGLE_THREAD_CLIENT_H_
-
-namespace cc {
-
-class LayerTreeHostSingleThreadClient {
- public:
-  // Request that the client schedule a composite.
-  virtual void ScheduleComposite() {}
-  // Request that the client schedule a composite now, and calculate appropriate
-  // delay for potential future frame.
-  virtual void ScheduleAnimation() {}
-
-  // Called whenever the compositor posts a SwapBuffers (either full or
-  // partial). After DidPostSwapBuffers(), exactly one of
-  // DidCompleteSwapBuffers() or DidAbortSwapBuffers() will be called, thus
-  // these functions can be used to keep track of pending swap buffers calls for
-  // rate limiting.
-  virtual void DidPostSwapBuffers() = 0;
-  virtual void DidCompleteSwapBuffers() = 0;
-  virtual void DidAbortSwapBuffers() = 0;
-
- protected:
-  virtual ~LayerTreeHostSingleThreadClient() {}
-};
-
-}  // namespace cc
-
-#endif  // CC_TREES_LAYER_TREE_HOST_SINGLE_THREAD_CLIENT_H_