use the metadata on canvas instead of on device

skia/ext/platform_canvas.cc

 // Copyright (c) 2011 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 "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
 #include "skia/ext/platform_device.h"
@@ skipping 59 matching lines @@
                                        OnFailureType failureType) {
   if (!device) {
     if (CRASH_ON_FAILURE == failureType)
       SK_CRASH();
     return nullptr;
   }
   return base::MakeUnique<SkCanvas>(device.get());
 }
 
 SkMetaData& GetMetaData(const SkCanvas& canvas) {
-  SkBaseDevice* device = canvas.getDevice();
-  DCHECK(device != nullptr);
-  return device->getMetaData();
+  return const_cast<SkCanvas&>(canvas).getMetaData();
 }
 
 #if defined(OS_MACOSX)
 void SetIsPreviewMetafile(const SkCanvas& canvas, bool is_preview) {
   SetBoolMetaData(canvas, kIsPreviewMetafileKey, is_preview);
 }
 
 bool IsPreviewMetafile(const SkCanvas& canvas) {
   return GetBoolMetaData(canvas, kIsPreviewMetafileKey);
 }
@@ skipping 19 matching lines @@
   if (platform_device) {
     // Compensate for drawing to a layer rather than the entire canvas
     SkMatrix ctm;
     SkIRect clip_bounds;
     canvas->temporary_internal_describeTopLayer(&ctm, &clip_bounds);
     native_drawing_context_ = platform_device->BeginPlatformPaint(ctm, clip_bounds);
   }
 }
 
 }  // namespace skia