Simplify platform_canvas.h by recognizing that PlatformCanvas does not actually extend

skia/ext/bitmap_platform_device_linux.cc

 // 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.
 
 #include "skia/ext/bitmap_platform_device_linux.h"
 #include "skia/ext/bitmap_platform_device_data.h"
 #include "skia/ext/platform_canvas.h"
 
 #if defined(OS_OPENBSD)
 #include <cairo.h>
@@ skipping 158 matching lines @@
   // Should never be called on Linux.
   SkASSERT(false);
 }
 
 void BitmapPlatformDevice::setMatrixClip(const SkMatrix& transform,
                                          const SkRegion& region,
                                          const SkClipStack&) {
   data_->SetMatrixClip(transform, region);
 }
 
+// PlatformCanvas impl
+
+SkCanvas* CreatePlatformCanvas(int width, int height, bool is_opaque,
+                               uint8_t* data, OnFailureType failureType) {
+  SkDevice* dev = BitmapPlatformDevice::Create(width, height, is_opaque, data);
+  return CreateCanvas(dev, failureType);
+}
+
 // Port of PlatformBitmap to linux
 
 PlatformBitmap::~PlatformBitmap() {
   cairo_destroy(surface_);
 }
 
 bool PlatformBitmap::Allocate(int width, int height, bool is_opaque) {
   cairo_surface_t* surf = cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
                                                      width, height);
   if (cairo_surface_status(surf) != CAIRO_STATUS_SUCCESS) {
     cairo_surface_destroy(surf);
     return false;
   }
 
   bitmap_.setConfig(SkBitmap::kARGB_8888_Config, width, height,
                     cairo_image_surface_get_stride(surf));
   bitmap_.setPixels(cairo_image_surface_get_data(surf));
   bitmap_.setIsOpaque(is_opaque);
 
   surface_ = cairo_create(surf);
   cairo_surface_destroy(surf);
   return true;
 }
     
 }  // namespace skia