cc: Add tile-free software compositing mode.

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 64 matching lines @@
 }
 
 void PicturePileImpl::Raster(
     SkCanvas* canvas,
     gfx::Rect canvas_rect,
     float contents_scale,
     RasterStats* raster_stats) {
 
   DCHECK(contents_scale >= min_contents_scale_);
 
-#ifndef NDEBUG
-  // Any non-painted areas will be left in this color.
-  canvas->clear(DebugColors::NonPaintedFillColor());
-#endif  // NDEBUG
-
   canvas->save();
   canvas->translate(-canvas_rect.x(), -canvas_rect.y());
 
   gfx::SizeF total_content_size = gfx::ScaleSize(tiling_.total_size(),
                                                  contents_scale);
   gfx::Rect total_content_rect(gfx::ToCeiledSize(total_content_size));
   gfx::Rect content_rect = total_content_rect;
   content_rect.Intersect(canvas_rect);
 
   // Clear one texel inside the right/bottom edge of the content rect,
@@ skipping 233 matching lines @@
           layer_rect_,
           *picture_list_iterator_);
       if (pixel_ref_iterator_)
         return;
     }
     ++tile_iterator_;
   } while (AdvanceToTileWithPictures());
 }
 
 }  // namespace cc