cc: Optimise shared tile handling in eviction tile priority queue.

cc/resources/eviction_tile_priority_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 "cc/resources/eviction_tile_priority_queue.h"
 
 namespace cc {
 
 namespace {
 
@@ skipping 134 matching lines @@
 Tile* EvictionTilePriorityQueue::PairedTilingSetQueue::Top(
     TreePriority tree_priority) {
   DCHECK(!IsEmpty());
 
   WhichTree next_tree = NextTileIteratorTree(tree_priority);
   TilingSetEvictionQueue* next_queue =
       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
   DCHECK(next_queue && !next_queue->IsEmpty());
 
   Tile* tile = next_queue->Top();
-  DCHECK(std::find(returned_shared_tiles.begin(),
-                   returned_shared_tiles.end(),
-                   tile) == returned_shared_tiles.end());
+  DCHECK(returned_tiles_for_debug.find(tile) == returned_tiles_for_debug.end());
   return tile;
 }
 
 void EvictionTilePriorityQueue::PairedTilingSetQueue::Pop(
     TreePriority tree_priority) {
   DCHECK(!IsEmpty());
 
   WhichTree next_tree = NextTileIteratorTree(tree_priority);
   TilingSetEvictionQueue* next_queue =
       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
   DCHECK(next_queue && !next_queue->IsEmpty());
-  returned_shared_tiles.push_back(next_queue->Top());
+  DCHECK(returned_tiles_for_debug.insert(next_queue->Top()).second);
   next_queue->Pop();
 
-  if (IsEmpty())
-    return;
-
-  next_tree = NextTileIteratorTree(tree_priority);
-  next_queue =
-      next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
-  while (std::find(returned_shared_tiles.begin(),
-                   returned_shared_tiles.end(),
-                   next_queue->Top()) != returned_shared_tiles.end()) {
-    next_queue->Pop();
-    if (IsEmpty())
-      break;
-    next_tree = NextTileIteratorTree(tree_priority);
-    next_queue =
-        next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
-  }
+  // If not empty, use Top to DCHECK the next iterator.
+  DCHECK_IMPLIES(!IsEmpty(), Top(tree_priority));
 }
 
 WhichTree
 EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree(
     TreePriority tree_priority) const {
   DCHECK(!IsEmpty());
 
   // If we only have one iterator with tiles, return it.
   if (!active_queue || active_queue->IsEmpty())
     return PENDING_TREE;
@@ skipping 20 matching lines @@
     return active_tile->required_for_activation() ? PENDING_TREE : ACTIVE_TREE;
   }
 
   // Return tile with a lower priority.
   if (pending_priority.IsHigherPriorityThan(active_priority))
     return ACTIVE_TREE;
   return PENDING_TREE;
 }
 
 }  // namespace cc