Keep the cairo clipping region in sync with the Skia one.

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 "third_party/skia/include/core/SkDevice.h"
 
-typedef struct _cairo_surface cairo_surface_t;
+typedef struct _cairo cairo_t;
 
 namespace skia {
 
 // Blindly copying the mac hierarchy.
 class PlatformDevice : public SkDevice {
  public:
-  typedef cairo_surface_t* PlatformSurface;
+  typedef cairo_t* PlatformSurface;
 
   // Returns if the preferred rendering engine is vectorial or bitmap based.
   virtual bool IsVectorial() = 0;
 
-  virtual cairo_surface_t* beginPlatformPaint() = 0;
+  virtual PlatformSurface beginPlatformPaint() = 0;
 
  protected:
   // Forwards |bitmap| to SkDevice's constructor.
   PlatformDevice(const SkBitmap& bitmap);
 };
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_DEVICE_LINUX_H_