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

cc/resources/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/content_layer_updater.h"
 
 #include "base/debug/trace_event.h"
 #include "base/time/time.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/layer_painter.h"
@@ skipping 17 matching lines @@
       painter_(painter.Pass()) {}
 
 ContentLayerUpdater::~ContentLayerUpdater() {}
 
 void ContentLayerUpdater::set_rendering_stats_instrumentation(
     RenderingStatsInstrumentation* rsi) {
   rendering_stats_instrumentation_ = rsi;
 }
 
 void ContentLayerUpdater::PaintContents(SkCanvas* canvas,
-                                        const gfx::Point& origin,
+                                        const gfx::Rect& content_rect,
                                         float contents_width_scale,
                                         float contents_height_scale,
                                         gfx::Rect* resulting_opaque_rect) {
   TRACE_EVENT0("cc", "ContentLayerUpdater::PaintContents");
   canvas->save();
-  canvas->translate(SkFloatToScalar(-origin.x()),
-                    SkFloatToScalar(-origin.y()));
+  canvas->translate(SkFloatToScalar(-content_rect.x()),
+                    SkFloatToScalar(-content_rect.y()));
 
-  SkISize size = canvas->getDeviceSize();
-  gfx::Rect content_rect(origin, gfx::Size(size.width(), size.height()));
+  // The |canvas| backing should be sized to hold the |content_rect|.
+  SkISize size = canvas->getBaseLayerSize();
+  CHECK_EQ(content_rect.width(), size.width());
+  CHECK_EQ(content_rect.height(), size.height());
 
   gfx::Rect layer_rect = content_rect;
-
   if (contents_width_scale != 1.f || contents_height_scale != 1.f) {
     canvas->scale(SkFloatToScalar(contents_width_scale),
                   SkFloatToScalar(contents_height_scale));
 
     layer_rect = gfx::ScaleToEnclosingRect(
         content_rect, 1.f / contents_width_scale, 1.f / contents_height_scale);
   }
 
   SkRect layer_sk_rect = SkRect::MakeXYWH(
       layer_rect.x(), layer_rect.y(), layer_rect.width(), layer_rect.height());
@@ skipping 20 matching lines @@
 
 void ContentLayerUpdater::SetOpaque(bool opaque) {
   layer_is_opaque_ = opaque;
 }
 
 void ContentLayerUpdater::SetFillsBoundsCompletely(bool fills_bounds) {
   layer_fills_bounds_completely_ = fills_bounds;
 }
 
 }  // namespace cc