Remove redundant signals_check_notifier_ schedule.

cc/tiles/tile_manager.cc

Index: cc/tiles/tile_manager.cc
diff --git a/cc/tiles/tile_manager.cc b/cc/tiles/tile_manager.cc
index e9a84a765293fe5619cd9e1fe77221a87ecb6ed1..9429510793ed313dac531fe45ec0e725dca0d95e 100644
--- a/cc/tiles/tile_manager.cc
+++ b/cc/tiles/tile_manager.cc
@@ -1220,11 +1220,9 @@ void TileManager::CheckIfMoreTilesNeedToBePrepared() {
   CHECK(tile_task_manager_);
   DCHECK(IsReadyToActivate());
   DCHECK(IsReadyToDraw());
+  // Signals notifier is already scheduled above in the same function.
   signals_.ready_to_activate = need_to_signal_activate;
   signals_.ready_to_draw = need_to_signal_draw;
-  // TODO(ericrk): Investigate why we need to schedule this (not just call it
-  // inline). http://crbug.com/498439
-  signals_check_notifier_.Schedule();
 }
 
 bool TileManager::MarkTilesOutOfMemory(