Align base::hash_map with C++11.

cc/trees/layer_tree_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_TREES_LAYER_TREE_IMPL_H_
 #define CC_TREES_LAYER_TREE_IMPL_H_
 
 #include <list>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/containers/hash_tables.h"
 #include "base/values.h"
 #include "cc/base/scoped_ptr_vector.h"
 #include "cc/base/swap_promise.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/output/renderer.h"
 #include "cc/resources/ui_resource_client.h"
 
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
-template<>
-struct hash<cc::LayerImpl*> {
-  size_t operator()(cc::LayerImpl* ptr) const {
-    return hash<size_t>()(reinterpret_cast<size_t>(ptr));
-  }
-};
-}  // namespace BASE_HASH_NAMESPACE
-#endif  // COMPILER
-
 namespace base {
 namespace debug {
 class TracedValue;
 }
 }
 
 namespace cc {
 
 class ContextProvider;
 class DebugRectHistory;
@@ skipping 350 matching lines @@
   float top_controls_delta_;
   float sent_top_controls_delta_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(LayerTreeImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_IMPL_H_