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 {
-
+#if 0
 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));
 }
-
+#endif
 }  // namespace skia