cc: Optimize TileManager::CleanUpReleasedTiles.

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 5d183ae55290c5ef6909462f62c34fe3225d2b55..1e3c132ab646e4078f458dcc236dfe711f34723b 100644
--- a/cc/resources/tile_manager.cc
+++ b/cc/resources/tile_manager.cc
@@ -277,12 +277,10 @@ void TileManager::FreeResourcesForReleasedTiles() {
 }
 
 void TileManager::CleanUpReleasedTiles() {
-  std::vector<Tile*>::iterator it = released_tiles_.begin();
-  while (it != released_tiles_.end()) {
-    Tile* tile = *it;
-
+  std::vector<Tile*> tiles_to_retain;

[enne (OOO), 2015/04/07 23:04:48]

Should you reserve this to be the number of tiles in released_tiles to avoid
unneeded allocations?

[vmpstr, 2015/04/07 23:10:23]

I'm not sure it's worth it, since the number of tiles that have a raster task is
bounded by a small number typically, and push_back is amortized constant. Number
of released tiles is technically not bounded on the other hand.

+  for (auto* tile : released_tiles_) {
     if (tile->HasRasterTask()) {
-      ++it;
+      tiles_to_retain.push_back(tile);
       continue;
     }
 
@@ -299,8 +297,8 @@ void TileManager::CleanUpReleasedTiles() {
     }
 
     delete tile;
-    it = released_tiles_.erase(it);
   }
+  released_tiles_.swap(tiles_to_retain);
 }
 
 void TileManager::DidFinishRunningTileTasks(TaskSet task_set) {