cc: Optimize decode scheduling for checker-images.

cc/tiles/tiling_set_raster_queue_all.cc

 // Copyright 2014 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/tiles/tiling_set_raster_queue_all.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 182 matching lines @@
   if (!IsTileValid(tile)) {
     current_tile_ = PrioritizedTile();
     return false;
   }
   current_tile_ = tiling_->MakePrioritizedTile(tile, priority_rect_type_);
   return true;
 }
 
 bool TilingSetRasterQueueAll::OnePriorityRectIterator::IsTileValid(
     const Tile* tile) const {
-  if (!tile || !TileNeedsRaster(tile))
+  if (!tile)
     return false;
+
+  bool should_process_tile_for_checker_imaging =
+      tile->is_checker_imaged() && tile->draw_info().requires_resource();
+  if (!TileNeedsRaster(tile) && !should_process_tile_for_checker_imaging)

[vmpstr, 2017/03/17 18:32:13]

TileNeedsRaster also has an occlusion check. I think that if the tile is
occluded then it shouldn't be processed for checker imaging either, so I think
you need to rework this a bit. 

[Khushal, 2017/03/27 13:57:33]

Done.

+    return false;
+
   // After the pending visible rect has been processed, we must return false
   // for pending visible rect tiles as tiling iterators do not ignore those
   // tiles.
   if (priority_rect_type_ > PictureLayerTiling::PENDING_VISIBLE_RECT) {
     gfx::Rect tile_bounds = tiling_data_->TileBounds(tile->tiling_i_index(),
                                                      tile->tiling_j_index());
     if (pending_visible_rect_.Intersects(tile_bounds))
       return false;
   }
   return true;
@@ skipping 223 matching lines @@
         current_tile_ = PrioritizedTile();
         return *this;
       }
       current_tile_ = *eventually_iterator_;
       break;
   }
   return *this;
 }
 
 }  // namespace cc