Add cc::SurfaceInfo::is_valid()

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index fa252c5a0969af8bf910bae02373c8d0c7777462..f068a9c33def7996ee9bf46db787f732f9b717e0 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1602,7 +1602,7 @@ CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
         surface_layer_impl->primary_surface_info().id());
     // We need to retain a reference to the fallback surface too so that it's
     // guaranteed to be available when needed.
-    if (surface_layer_impl->fallback_surface_info().id().is_valid()) {
+    if (surface_layer_impl->fallback_surface_info().is_valid()) {
       metadata.referenced_surfaces.push_back(
           surface_layer_impl->fallback_surface_info().id());
     }