Put the Pepper stuff in the content namespace.

content/renderer/pepper/pepper_platform_context_3d_impl.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_RENDERER_PEPPER_PEPPER_PLATFORM_CONTEXT_3D_IMPL_H_
 #define CONTENT_RENDERER_PEPPER_PEPPER_PLATFORM_CONTEXT_3D_IMPL_H_
 #pragma once
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "webkit/plugins/ppapi/plugin_delegate.h"
 
 #ifdef ENABLE_GPU
 
 namespace gpu {
 
 class CommandBuffer;
 
 }  // namespace gpu
 
 class CommandBufferProxy;
 class GpuChannelHost;
+class ContentGLContext;
+
+namespace content {
+
 class PepperParentContextProvider;
-class ContentGLContext;
 
 class PlatformContext3DImpl
     : public webkit::ppapi::PluginDelegate::PlatformContext3D {
  public:
   explicit PlatformContext3DImpl(
       PepperParentContextProvider* parent_context_provider);
   virtual ~PlatformContext3DImpl();
 
   virtual bool Init(const int32* attrib_list) OVERRIDE;
   virtual unsigned GetBackingTextureId() OVERRIDE;
@@ skipping 15 matching lines @@
   base::WeakPtr<ContentGLContext> parent_context_;
   scoped_refptr<GpuChannelHost> channel_;
   unsigned int parent_texture_id_;
   bool has_alpha_;
   CommandBufferProxy* command_buffer_;
   base::Closure context_lost_callback_;
   ConsoleMessageCallback console_message_callback_;
   base::WeakPtrFactory<PlatformContext3DImpl> weak_ptr_factory_;
 };
 
+}  // namespace content
+
 #endif  // ENABLE_GPU
 
 #endif  // CONTENT_RENDERER_PEPPER_PEPPER_PLATFORM_CONTEXT_3D_IMPL_H_