Smart layer invalidation for LCD text.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index e69d3217044ca3e7e47f36ad1cc4e230948a73ed..db85a34b3b834583be9d5d1423ed644e68c0e10d 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -853,10 +853,7 @@ void PictureLayerImpl::UpdateLCDTextStatus() {
   pending_layer->is_using_lcd_text_ = is_using_lcd_text_;
   pending_layer->pile_ = PicturePileImpl::CreateFromOther(pending_layer->pile_,
                                                           is_using_lcd_text_);
-
-  // TODO(enne): if we tracked text regions, we could just invalidate those
-  // directly rather than tossing away every tile.
-  pending_layer->tilings_->Invalidate(gfx::Rect(bounds()));
+  pending_layer->tilings_->InvalidateTilesWithText();
 }
 
 void PictureLayerImpl::ResetRasterScale() {