cc: Use multiple PrepareTiles approaches

cc/resources/picture_layer_tiling.cc

Index: cc/resources/picture_layer_tiling.cc
diff --git a/cc/resources/picture_layer_tiling.cc b/cc/resources/picture_layer_tiling.cc
index b90d28d19ad4d1424dc7b388372223df367ca5b7..8fed885f2b2bf96a52a846683f1af7917bed60e0 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -800,6 +800,14 @@ bool PictureLayerTiling::IsTileRequiredForDraw(const Tile* tile) const {
   return true;
 }
 
+bool PictureLayerTiling::RasterSourceCoversCurrentVisibleTiles() const {

[brianderson, 2015/05/19 02:40:35]

Is this correct?

[enne (OOO), 2015/05/19 22:53:41]

Seems legit!

+  gfx::Rect visible_rect_expanded_to_tile_bounds =
+      tiling_data_.ExpandRectToTileBounds(current_visible_rect_);
+
+  return raster_source_->CoversRect(visible_rect_expanded_to_tile_bounds,
+                                    contents_scale_);
+}
+
 void PictureLayerTiling::UpdateRequiredStatesOnTile(Tile* tile) const {
   DCHECK(tile);
   tile->set_required_for_activation(IsTileRequiredForActivation(tile));