Fix a proto-type mismatch on a virtual override.

src/base/gfx/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 "base/gfx/platform_canvas_linux.h"
 
 #include "base/gfx/platform_device_linux.h"
 #include "base/gfx/bitmap_platform_device_linux.h"
 #include "base/logging.h"
 
@@ skipping 20 matching lines @@
   device->unref(); // was created with refcount 1, and setDevice also refs
   return true;
 }
 
 PlatformDeviceLinux& PlatformCanvasLinux::getTopPlatformDevice() const {
   // All of our devices should be our special PlatformDevice.
   SkCanvas::LayerIter iter(const_cast<PlatformCanvasLinux*>(this), false);
   return *static_cast<PlatformDeviceLinux*>(iter.device());
 }
 
-SkDevice* PlatformCanvasLinux::createDevice(SkBitmap::Config, int width,
-                                            int height, bool is_opaque) {
+SkDevice* PlatformCanvasLinux::createDevice(SkBitmap::Config config,
+                                            int width,
+                                            int height,
+                                            bool is_opaque, bool isForLayer) {
+  DCHECK(config == SkBitmap::kARGB_8888_Config);
   return createPlatformDevice(width, height, is_opaque);
 }
 
 SkDevice* PlatformCanvasLinux::createPlatformDevice(int width,
                                                     int height,
                                                     bool is_opaque) {
   return BitmapPlatformDeviceLinux::Create(width, height, is_opaque);
 }
 
 }  // namespace gfx