cc: Optimise eviction tile priority queue

cc/resources/tiling_set_eviction_queue.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 <utility>
 
 #include "cc/resources/tiling_set_eviction_queue.h"
 
 namespace cc {
 
@@ skipping 202 matching lines @@
       current_tiling_range_type_ =
           PictureLayerTilingSet::BETWEEN_HIGH_AND_LOW_RES;
       return true;
     case PictureLayerTilingSet::BETWEEN_HIGH_AND_LOW_RES:
       current_tiling_range_type_ = PictureLayerTilingSet::LOW_RES;
       return true;
     case PictureLayerTilingSet::LOW_RES:
       current_tiling_range_type_ = PictureLayerTilingSet::HIGH_RES;
       return true;
     case PictureLayerTilingSet::HIGH_RES:
+      // Process required for activation tiles (unless that has already been
+      // done for the current priority bin) if there is a tiling with required
+      // for activation tiles and that tiling may have required for activation
+      // tiles having the current priority bin (in the pending tree only NOW
+      // tiles may be required for activation).
       if (!processing_tiling_with_required_for_activation_tiles_ &&
           tiling_index_with_required_for_activation_tiles_ <
-              tiling_set_->num_tilings()) {
+              tiling_set_->num_tilings() &&
+          (current_priority_bin_ == TilePriority::NOW ||
+           tree_ == ACTIVE_TREE)) {
         processing_tiling_with_required_for_activation_tiles_ = true;
         return true;
       }
       processing_tiling_with_required_for_activation_tiles_ = false;
 
       if (!AdvanceToNextPriorityBin())
         return false;
 
       current_tiling_range_type_ = PictureLayerTilingSet::HIGHER_THAN_HIGH_RES;
       return true;
@@ skipping 156 matching lines @@
           tiling_set_->client()->GetPendingOrActiveTwinTiling(tiling);
       if (pending_tiling && pending_tiling->resolution() == HIGH_RESOLUTION)
         return i;
     }
   }
 
   return num_tilings;
 }
 
 }  // namespace cc