Move the "platform" wrappers in skia/ext to the skia namespace.

skia/ext/platform_device_linux.h

 // Copyright (c) 2006-2008 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 SKIA_EXT_PLATFORM_DEVICE_LINUX_H_
 #define SKIA_EXT_PLATFORM_DEVICE_LINUX_H_
 
 #include "SkDevice.h"
 
-namespace gfx {
+namespace skia {
 
 // Blindly copying the mac hierarchy.
 class PlatformDeviceLinux : public SkDevice {
  public:
   // Returns if the preferred rendering engine is vectorial or bitmap based.
   virtual bool IsVectorial() = 0;
 
  protected:
   // Forwards |bitmap| to SkDevice's constructor.
   PlatformDeviceLinux(const SkBitmap& bitmap);
 };
 
-}  // namespace gfx
+}  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_DEVICE_LINUX_H_