cc: Add tile pool to tile manager.

cc/resources/tile_manager.cc

Index: cc/resources/tile_manager.cc
diff --git a/cc/resources/tile_manager.cc b/cc/resources/tile_manager.cc
index b2e536fa8aaf87b9560e326a012890a7b2289004..61245c71ca5306e84fc61708955f4f24dc376923 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -154,6 +154,7 @@ inline ManagedTileBin BinFromTilePriority(const TilePriority& prio) {
 // gives us an insurance that we're not spending a huge amount
 // of time scheduling one enormous set of tasks.
 const size_t kMaxRasterTasks = 256u;
+const size_t kTilePoolSize = 256u;
 
 }  // namespace
 
@@ -213,6 +214,7 @@ TileManager::TileManager(
       did_initialize_visible_tile_(false),
       did_check_for_completed_tasks_since_last_schedule_tasks_(true) {
   raster_worker_pool_->SetClient(this);
+  tile_pool_.reserve(kTilePoolSize);
 }
 
 TileManager::~TileManager() {
@@ -223,6 +225,10 @@ TileManager::~TileManager() {
   CleanUpReleasedTiles();
   DCHECK_EQ(0u, tiles_.size());
 
+  for (size_t i = 0; i < tile_pool_.size(); ++i)
+    delete tile_pool_[i];
+  tile_pool_.clear();
+
   RasterWorkerPool::RasterTask::Queue empty;
   raster_worker_pool_->ScheduleTasks(&empty);
 
@@ -253,8 +259,14 @@ void TileManager::CleanUpReleasedTiles() {
        it != released_tiles_.end();
        ++it) {
     Tile* tile = *it;
+    ManagedTileState& mts = tile->managed_state();
 
-    FreeResourcesForTile(tile);
+    for (int mode = 0; mode < NUM_RASTER_MODES; ++mode) {
+      FreeResourceForTile(tile, static_cast<RasterMode>(mode));
+      mts.tile_versions[mode].set_use_resource();
+      mts.tile_versions[mode].raster_task_.Reset();
+    }
+    tile->reset_picture_pile();
 
     DCHECK(tiles_.find(tile->id()) != tiles_.end());
     tiles_.erase(tile->id());
@@ -267,7 +279,10 @@ void TileManager::CleanUpReleasedTiles() {
       image_decode_tasks_.erase(tile->layer_id());
     }
 
-    delete tile;
+    if (tile_pool_.size() < kTilePoolSize)
+      tile_pool_.push_back(tile);
+    else
+      delete tile;
   }
 
   released_tiles_.clear();
@@ -816,7 +831,7 @@ RasterWorkerPool::RasterTask TileManager::CreateRasterTask(Tile* tile) {
 
   scoped_ptr<ResourcePool::Resource> resource =
       resource_pool_->AcquireResource(
-          tile->tile_size_.size(),
+          tile->tile_size_,
           raster_worker_pool_->GetResourceFormat());
   const Resource* const_resource = resource.get();
 
@@ -939,15 +954,23 @@ scoped_refptr<Tile> TileManager::CreateTile(PicturePileImpl* picture_pile,
                                             int layer_id,
                                             int source_frame_number,
                                             bool can_use_lcd_text) {
-  scoped_refptr<Tile> tile = make_scoped_refptr(new Tile(this,
-                                                         picture_pile,
-                                                         tile_size,
-                                                         content_rect,
-                                                         opaque_rect,
-                                                         contents_scale,
-                                                         layer_id,
-                                                         source_frame_number,
-                                                         can_use_lcd_text));
+  scoped_refptr<Tile> tile;
+  if (!tile_pool_.empty()) {
+    tile = make_scoped_refptr(tile_pool_.back());
+    tile_pool_.pop_back();
+  } else {
+    tile = make_scoped_refptr(new Tile(this));
+  }
+
+  tile->Reset(picture_pile,
+              tile_size,
+              content_rect,
+              opaque_rect,
+              contents_scale,
+              layer_id,
+              source_frame_number,
+              can_use_lcd_text);
+
   DCHECK(tiles_.find(tile->id()) == tiles_.end());
 
   tiles_[tile->id()] = tile;