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

skia/ext/platform_canvas_win.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 <windows.h>
-#include <psapi.h>
-
-#include "base/debug/trace_event.h"
-#include "skia/ext/bitmap_platform_device_win.h"
-#include "skia/ext/platform_canvas.h"
-
-namespace skia {
-
-PlatformCanvas::PlatformCanvas(int width, int height, bool is_opaque) {
-  TRACE_EVENT2("skia", "PlatformCanvas::PlatformCanvas",
-               "width", width, "height", height);
-  initialize(width, height, is_opaque, NULL);
-}
-
-PlatformCanvas::PlatformCanvas(int width,
-                               int height,
-                               bool is_opaque,
-                               HANDLE shared_section) {
-  TRACE_EVENT2("skia", "PlatformCanvas::PlatformCanvas",
-               "width", width, "height", height);
-  initialize(width, height, is_opaque, shared_section);
-}
-
-PlatformCanvas::~PlatformCanvas() {
-}
-
-bool PlatformCanvas::initialize(int width,
-                               int height,
-                               bool is_opaque,
-                               HANDLE shared_section) {
-  return initializeWithDevice(BitmapPlatformDevice::Create(
-      width, height, is_opaque, shared_section));
-}
-
-}  // namespace skia