cc: Do not cleanup tiles with raster tasks.

cc/resources/prioritized_tile_set.cc

Index: cc/resources/prioritized_tile_set.cc
diff --git a/cc/resources/prioritized_tile_set.cc b/cc/resources/prioritized_tile_set.cc
index b7b3b5a741eee424707201abc7453cfbb776d115..0085ca12c9d2c44e0ac94b1d96fd4f8b9f72948d 100644
--- a/cc/resources/prioritized_tile_set.cc
+++ b/cc/resources/prioritized_tile_set.cc
@@ -81,6 +81,15 @@ void PrioritizedTileSet::Clear() {
   }
 }
 
+bool PrioritizedTileSet::Empty() {
+  for (int bin = 0; bin < NUM_BINS; ++bin) {
+    if (!tiles_[bin].empty()) {
+      return false;
+    }

[reveman, 2014/07/28 15:50:53]

nit: no need for "{" "}" here

[sohanjg, 2014/07/30 11:12:57]

Done.

+  }
+  return true;
+}
+
 void PrioritizedTileSet::SortBinIfNeeded(ManagedTileBin bin) {
   if (!bin_sorted_[bin]) {
     SortBinTiles(bin, &tiles_[bin]);