cc: Support mask layers in impl-side painting

cc/picture_layer_tiling.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 "cc/picture_layer_tiling.h"
 
 #include "cc/math_util.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 
@@ skipping 265 matching lines @@
     const gfx::Transform& last_screen_transform,
     const gfx::Transform& current_screen_transform,
     double time_delta) {
   gfx::Rect content_rect = ContentRect();
   if (content_rect.IsEmpty())
     return;
 
   gfx::Rect view_rect(gfx::Point(), device_viewport);
   int right = tiling_data_.TileXIndexFromSrcCoord(content_rect.width() - 1);
   int bottom = tiling_data_.TileYIndexFromSrcCoord(content_rect.height() - 1);
+
   for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
     TileMapKey key = it->first;
     TilePriority priority;
     if (key.first > right || key.second > bottom) {
       priority.distance_to_visible_in_pixels = std::numeric_limits<int>::max();
       priority.time_to_visible_in_seconds =
           TilePriority::kMaxTimeToVisibleInSeconds;
-      // TODO(qinmin): pass the correct tree to this function.
       it->second->set_priority(tree, priority);
       continue;
     }
 
     gfx::Rect tile_bound = tiling_data_.TileBounds(key.first, key.second);
     gfx::RectF layer_content_rect = gfx::ScaleRect(
         tile_bound,
         layer_content_scale_x / contents_scale_,
         layer_content_scale_y / contents_scale_);
     gfx::RectF screen_rect = MathUtil::mapClippedRect(
         current_screen_transform, layer_content_rect);
     gfx::RectF previous_rect = MathUtil::mapClippedRect(
         last_screen_transform, layer_content_rect);
 
     priority.resolution = HIGH_RESOLUTION;
     priority.time_to_visible_in_seconds =
         TilePriority::TimeForBoundsToIntersect(
             previous_rect, screen_rect, time_delta, view_rect);
 
     priority.distance_to_visible_in_pixels =
         TilePriority::manhattanDistance(screen_rect, view_rect);
-    // TODO(qinmin): pass the correct tree to this function.
     it->second->set_priority(tree, priority);
   }
 }
 
 }  // namespace cc