cc: DCHECK that the OutputSurface was released in ~LayerTreeHostImpl().

cc/test/fake_layer_tree_host_impl.cc

Index: cc/test/fake_layer_tree_host_impl.cc
diff --git a/cc/test/fake_layer_tree_host_impl.cc b/cc/test/fake_layer_tree_host_impl.cc
index d8d79567892a23a64bf7a2643617df63f1d62ec8..43713d0a1d509883c5c0eb3b12f63c94bca1c422 100644
--- a/cc/test/fake_layer_tree_host_impl.cc
+++ b/cc/test/fake_layer_tree_host_impl.cc
@@ -62,7 +62,9 @@ FakeLayerTreeHostImpl::FakeLayerTreeHostImpl(
       CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE, time_ticks));
 }
 
-FakeLayerTreeHostImpl::~FakeLayerTreeHostImpl() {}
+FakeLayerTreeHostImpl::~FakeLayerTreeHostImpl() {
+  ReleaseOutputSurface();
+}
 
 void FakeLayerTreeHostImpl::CreatePendingTree() {
   LayerTreeHostImpl::CreatePendingTree();