cc: Remove TiledLayer mask DCHECK for 0 tiles

cc/layers/tiled_layer_impl.cc

Index: cc/layers/tiled_layer_impl.cc
diff --git a/cc/layers/tiled_layer_impl.cc b/cc/layers/tiled_layer_impl.cc
index aea456727e33e9c6a0fd417a78a4c11d42f0b885..d2767cf02eff991ada2d1520f78b7e31d63f9fad 100644
--- a/cc/layers/tiled_layer_impl.cc
+++ b/cc/layers/tiled_layer_impl.cc
@@ -54,6 +54,12 @@ TiledLayerImpl::~TiledLayerImpl() {
 ResourceProvider::ResourceId TiledLayerImpl::ContentsResourceId() const {
   // This function is only valid for single texture layers, e.g. masks.
   DCHECK(tiler_);
+  // It's possible the mask layer is created but has no size or otherwise
+  // can't draw.
+  if (tiler_->num_tiles_x() == 0 || tiler_->num_tiles_y() == 0)
+    return 0;
+
+  // Any other number of tiles other than 0 or 1 is incorrect for masks.
   DCHECK_EQ(tiler_->num_tiles_x(), 1);
   DCHECK_EQ(tiler_->num_tiles_y(), 1);