Update from https://crrev.com/304418

cc/resources/scoped_gpu_raster.h

 // Copyright 2014 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_RESOURCES_SCOPED_GPU_RASTER_H_
 #define CC_RESOURCES_SCOPED_GPU_RASTER_H_
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/context_provider.h"
 
 namespace cc {
 
 // The following class is needed to modify GL resources using GPU
 // raster. The user must ensure that they only use GPU raster on
 // GL resources while an instance of this class is alive.
 class CC_EXPORT ScopedGpuRaster {
  public:
-  ScopedGpuRaster(ContextProvider* context_provider);
+  explicit ScopedGpuRaster(ContextProvider* context_provider);
   ~ScopedGpuRaster();
 
  private:
   void BeginGpuRaster();
   void EndGpuRaster();
 
   ContextProvider* context_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedGpuRaster);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_SCOPED_GPU_RASTER_H_