cc: Speed up CleanUpImageDecodeTasks a bit.

cc/resources/tile_manager_perftest.cc

Index: cc/resources/tile_manager_perftest.cc
diff --git a/cc/resources/tile_manager_perftest.cc b/cc/resources/tile_manager_perftest.cc
index 49651322544a3c5de4e094f2f90bd6d922090bb0..bd35ab5cd67fc82609cabc3cd6be4c0ca93586ef 100644
--- a/cc/resources/tile_manager_perftest.cc
+++ b/cc/resources/tile_manager_perftest.cc
@@ -46,7 +46,9 @@ class TileManagerPerfTest : public testing::Test {
     GlobalStateThatImpactsTilePriority state;
     gfx::Size tile_size = settings_.default_tile_size;
     state.memory_limit_in_bytes =
-        10000 * 4 * tile_size.width() * tile_size.height();
+        10000u * 4u *
+        static_cast<size_t>(tile_size.width() * tile_size.height());
+    state.num_resources_limit = 10000;
     state.memory_limit_policy = ALLOW_ANYTHING;
     state.tree_priority = SMOOTHNESS_TAKES_PRIORITY;
 
@@ -148,6 +150,7 @@ class TileManagerPerfTest : public testing::Test {
       }
 
       tile_manager_->ManageTiles();
+      tile_manager_->CheckForCompletedTasks();
       timer_.NextLap();
     } while (!timer_.HasTimeLimitExpired());