cc: Give non-drawing layers that are rasterized a lower priority.

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 12395 matching lines @@
     if (tile->tiling_i_index() < 2 && tile->tiling_j_index() < 2)
       EXPECT_TRUE(tile->HasRasterTask());
     else
       EXPECT_FALSE(tile->HasRasterTask());
   }
   Region expected_invalidation(
       raster_source->GetRectForImage(checkerable_image.stable_id()));
   EXPECT_EQ(expected_invalidation, *(root->GetPendingInvalidation()));
 }
 
+TEST_F(LayerTreeHostImplTest, RasterTilePrioritizationForNonDrawingLayers) {
+  host_impl_->SetViewportSize(gfx::Size(500, 500));
+}
+
 }  // namespace
 }  // namespace cc