Implement a method to access the non-composited content root layer picture pile.

cc/picture_pile_impl.cc

 // Copyright 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 "base/debug/trace_event.h"
 #include "cc/picture_pile_impl.h"
 #include "cc/rendering_stats.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkSize.h"
 #include "ui/gfx/rect_conversions.h"
@@ skipping 71 matching lines @@
 void PicturePileImpl::GatherPixelRefs(
     const gfx::Rect& rect, std::list<skia::LazyPixelRef*>& pixel_refs) {
   std::list<skia::LazyPixelRef*> result;
   for (PicturePile::Pile::const_iterator i = pile_.begin();
       i != pile_.end(); ++i) {
     (*i)->GatherPixelRefs(rect, result);
     pixel_refs.splice(pixel_refs.end(), result);
   }
 }
 
+gfx::Rect PicturePileImpl::LayerRect() const {
+  gfx::Rect layer_rect;
+  for (PicturePile::Pile::const_iterator i = pile_.begin();
+      i != pile_.end(); ++i) {
+    layer_rect.Union((*i)->LayerRect());
+  }
+  return layer_rect;
+}
+
 }  // namespace cc