Cleanup: Pass std::string as const reference from content/

content/common/gpu/gpu_channel_manager.h

 // Copyright (c) 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 CONTENT_COMMON_GPU_GPU_CHANNEL_MANAGER_H_
 #define CONTENT_COMMON_GPU_GPU_CHANNEL_MANAGER_H_
 
 #include <deque>
 #include <string>
 #include <vector>
@@ skipping 127 matching lines @@
                           bool allow_real_time_streams);
   void OnCloseChannel(const IPC::ChannelHandle& channel_handle);
   void OnVisibilityChanged(
       int32 render_view_id, int32 client_id, bool visible);
   void OnCreateViewCommandBuffer(
       const gfx::GLSurfaceHandle& window,
       int32 render_view_id,
       int32 client_id,
       const GPUCreateCommandBufferConfig& init_params,
       int32 route_id);
-  void OnLoadedShader(std::string shader);
+  void OnLoadedShader(const std::string& shader);
   void DestroyGpuMemoryBuffer(gfx::GpuMemoryBufferId id, int client_id);
   void DestroyGpuMemoryBufferOnIO(gfx::GpuMemoryBufferId id, int client_id);
   void OnDestroyGpuMemoryBuffer(gfx::GpuMemoryBufferId id,
                                 int client_id,
                                 int32 sync_point);
 
   void OnUpdateValueState(int client_id,
                           unsigned int target,
                           const gpu::ValueState& state);
   void OnLoseAllContexts();
@@ skipping 22 matching lines @@
   // that any WeakPtrs to Controller are invalidated before its members
   // variable's destructors are executed, rendering them invalid.
   base::WeakPtrFactory<GpuChannelManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuChannelManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_GPU_CHANNEL_MANAGER_H_