cc: Move prepaint region calculations to the tiling set.

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 12fc720a7604db0bec6621247fe7d108d7dff3b8..f41be32906cd855d5a3b3e2e84b989e148c59ed2 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -2277,7 +2277,8 @@ TEST_F(PictureLayerImplTest, ShareTilesOnNextFrame) {
   EXPECT_TRUE(pending_tiling->TileAt(1, 1));
 
   // Drop the tiles on the active tree and recreate them.
-  active_tiling->ComputeTilePriorityRects(gfx::Rect(), 1.f, 1.0, Occlusion());
+  active_layer_->tilings()->UpdateTilePriorities(gfx::Rect(), 1.f, 1.0,
+                                                 Occlusion(), true);
   EXPECT_TRUE(active_tiling->AllTilesForTesting().empty());
   active_tiling->CreateAllTilesForTesting();