Remove parts of //cc we aren't using

cc/layers/layer_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_LAYERS_LAYER_CLIENT_H_
-#define CC_LAYERS_LAYER_CLIENT_H_
-
-#include <string>
-
-#include "base/memory/ref_counted.h"
-#include "cc/base/cc_export.h"
-
-namespace base {
-namespace trace_event {
-class ConvertableToTraceFormat;
-}
-}
-
-namespace cc {
-
-class CC_EXPORT LayerClient {
- public:
-  // Returns a pointer to a debug info object, if one has been computed.
-  // If not, returns nullptr.
-  // If the returned pointer is non-nullptr, the caller takes
-  // ownership of the pointer.
-  virtual scoped_refptr<base::trace_event::ConvertableToTraceFormat>
-      TakeDebugInfo() = 0;
-
- protected:
-  virtual ~LayerClient() {}
-};
-
-}  // namespace cc
-
-#endif  // CC_LAYERS_LAYER_CLIENT_H_