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

cc/resources/bitmap_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/bitmap_content_layer_updater.h"
 
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/layer_painter.h"
 #include "cc/resources/prioritized_resource.h"
@@ skipping 49 matching lines @@
     float contents_width_scale,
     float contents_height_scale,
     gfx::Rect* resulting_opaque_rect) {
   if (canvas_size_ != content_rect.size()) {
     devtools_instrumentation::ScopedLayerTask paint_setup(
         devtools_instrumentation::kPaintSetup, layer_id_);
     canvas_size_ = content_rect.size();
     bitmap_backing_.allocN32Pixels(
         canvas_size_.width(), canvas_size_.height(), layer_is_opaque_);
     canvas_ = skia::AdoptRef(new SkCanvas(bitmap_backing_));
+    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_.get(),
-                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_->AddPaint(
       duration,
       content_rect.width() * content_rect.height());
 }
 
@@ skipping 22 matching lines @@
 void BitmapContentLayerUpdater::SetOpaque(bool opaque) {
   if (opaque != layer_is_opaque_) {
     canvas_.clear();
     canvas_size_ = gfx::Size();
   }
 
   ContentLayerUpdater::SetOpaque(opaque);
 }
 
 }  // namespace cc