cc: Don't analyze masks for solid color.

We don't handle masks that are solid color. Also, I suspect that most
masks aren't solid color, so we shouldn't waste time analyzing them.

R=enne, danakj

Review URL: https://codereview.chromium.org/543853002

Cr-Commit-Position: refs/heads/master@{#293606}

cc/layers/picture_layer_impl.cc

@@ -582,12 +582,16 @@ scoped_refptr<Tile> PictureLayerImpl::CreateTile(PictureLayerTiling* tiling,
   if (!pile_->CanRaster(tiling->contents_scale(), content_rect))
     return scoped_refptr<Tile>();
 
+  int flags = 0;
+
   // TODO(vmpstr): Revisit this. For now, enabling analysis means that we get as
   // much savings on memory as we can. However, for some cases like ganesh or
   // small layers, the amount of time we spend analyzing might not justify
-  // memory savings that we can get.
+  // memory savings that we can get. Note that we don't handle solid color
+  // masks, so we shouldn't bother analyzing those.
   // Bugs: crbug.com/397198, crbug.com/396908
-  int flags = Tile::USE_PICTURE_ANALYSIS;
+  if (!is_mask_)
+    flags = Tile::USE_PICTURE_ANALYSIS;
 
   return layer_tree_impl()->tile_manager()->CreateTile(
       pile_.get(),