Add flag for drawing layers to screen with Ganesh

cc/resources/picture_pile_impl.h

Index: cc/resources/picture_pile_impl.h
diff --git a/cc/resources/picture_pile_impl.h b/cc/resources/picture_pile_impl.h
index f3bc98cbc479cbb155ec2dbf48ead9cd0783206d..92c0fb3f4e96e2925843807787428a5e1e6e85bc 100644
--- a/cc/resources/picture_pile_impl.h
+++ b/cc/resources/picture_pile_impl.h
@@ -47,7 +47,16 @@ class CC_EXPORT PicturePileImpl : public PicturePileBase {
   // NULL. When slow-down-raster-scale-factor is set to a value
   // greater than 1, the reported rasterize time is the minimum
   // measured value over all runs.
-  void Raster(
+  void RasterDirect(
+      SkCanvas* canvas,
+      gfx::Rect canvas_rect,
+      float contents_scale,
+      RasterStats* raster_stats);
+
+  // Similar to the above RasterDirect method, but this is a convenience method
+  // for when it is known that the raster is going to an intermediate bitmap
+  // that itself will then be blended and thus that a canvas clear is required.
+  void RasterToBitmap(
       SkCanvas* canvas,
       gfx::Rect canvas_rect,
       float contents_scale,