cc: Add CHECKs that the backing size reported by canvas matches.

cc/resources/skpicture_content_layer_updater.cc

 // Copyright 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 "cc/resources/skpicture_content_layer_updater.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/layer_painter.h"
 #include "cc/resources/prioritized_resource.h"
@@ skipping 11 matching lines @@
 SkPictureContentLayerUpdater::~SkPictureContentLayerUpdater() {}
 
 void SkPictureContentLayerUpdater::PrepareToUpdate(
     const gfx::Rect& content_rect,
     const gfx::Size&,
     float contents_width_scale,
     float contents_height_scale,
     gfx::Rect* resulting_opaque_rect) {
   SkCanvas* canvas =
       picture_.beginRecording(content_rect.width(), content_rect.height());
+  SkISize size = canvas->getBaseLayerSize();
+  CHECK_EQ(content_rect.width(), size.width());
+  CHECK_EQ(content_rect.height(), size.height());
   base::TimeTicks start_time =
       rendering_stats_instrumentation_->StartRecording();
   PaintContents(canvas,
-                content_rect.origin(),
+                content_rect,
                 contents_width_scale,
                 contents_height_scale,
                 resulting_opaque_rect);
   base::TimeDelta duration =
       rendering_stats_instrumentation_->EndRecording(start_time);
   rendering_stats_instrumentation_->AddRecord(
       duration, content_rect.width() * content_rect.height());
   picture_.endRecording();
 }
 
 void SkPictureContentLayerUpdater::DrawPicture(SkCanvas* canvas) {
   TRACE_EVENT0("cc", "SkPictureContentLayerUpdater::DrawPicture");
   canvas->drawPicture(picture_);
 }
 
 }  // namespace cc