cc: Inflate invalidation in each picture list

cc/resources/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 <algorithm>
 #include <limits>
 
 #include "base/debug/trace_event.h"
 #include "cc/base/region.h"
 #include "cc/debug/debug_colors.h"
@@ skipping 133 matching lines @@
     // pictures on top are not overdrawn by pictures on the bottom.
     for (PictureList::reverse_iterator i = pic_list.rbegin();
          i != pic_list.rend(); ++i) {
       // This is intentionally *enclosed* rect, so that the clip is aligned on
       // integral post-scale content pixels and does not extend past the edges
       // of the picture's layer rect.  The min_contents_scale enforces that
       // enough buffer pixels have been added such that the enclosed rect
       // encompasses all invalidated pixels at any larger scale level.
       gfx::Rect content_clip = gfx::ToEnclosedRect(
           gfx::ScaleRect((*i)->LayerRect(), contents_scale));
-      DCHECK(!content_clip.IsEmpty());
+      DCHECK(!content_clip.IsEmpty()) <<
+          "Layer rect: " << (*i)->LayerRect().ToString() <<
+          "Contents scale: " << contents_scale;
       if (!unclipped.Intersects(content_clip))
         continue;
 
       base::TimeDelta total_duration =
           base::TimeDelta::FromInternalValue(0);
       base::TimeDelta best_duration =
           base::TimeDelta::FromInternalValue(std::numeric_limits<int64>::max());
       int repeat_count = std::max(1, slow_down_raster_scale_factor_for_debug_);
 
       for (int j = 0; j < repeat_count; ++j) {
@@ skipping 163 matching lines @@
           layer_rect_,
           *picture_list_iterator_);
       if (pixel_ref_iterator_)
         return;
     }
     ++tile_iterator_;
   } while (AdvanceToTileWithPictures());
 }
 
 }  // namespace cc