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

skia/ext/platform_canvas_linux.cc

 // 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.
 
 #include "skia/ext/platform_canvas.h"
 
 #include <cairo/cairo.h>
 
 #include "skia/ext/platform_device_linux.h"
 #include "skia/ext/bitmap_platform_device_linux.h"
@@ skipping 24 matching lines @@
   SkDevice* device =
       BitmapPlatformDevice::Create(width, height, is_opaque, data);
   if (!device)
     return false;
 
   setDevice(device);
   device->unref(); // was created with refcount 1, and setDevice also refs
   return true;
 }
 
-cairo_surface_t* PlatformCanvas::beginPlatformPaint() {
+cairo_t* PlatformCanvas::beginPlatformPaint() {
   return getTopPlatformDevice().beginPlatformPaint();
 }
 
 void PlatformCanvas::endPlatformPaint() {
   // We don't need to do anything on Linux here.
 }
 
 SkDevice* PlatformCanvas::createDevice(SkBitmap::Config config,
                                        int width,
                                        int height,
                                        bool is_opaque,
                                        bool isForLayer) {
   SkASSERT(config == SkBitmap::kARGB_8888_Config);
   return BitmapPlatformDevice::Create(width, height, is_opaque);
 }
 
 }  // namespace skia