cc: Allow the main thread to cancel commits

cc/trees/layer_tree_host_unittest_damage.cc

Index: cc/trees/layer_tree_host_unittest_damage.cc
diff --git a/cc/trees/layer_tree_host_unittest_damage.cc b/cc/trees/layer_tree_host_unittest_damage.cc
index 0feabf7ef4d233b396ed2dec999aeb8b8af2719f..3d444066d24e833102e5c5a70678676efa0e4c46 100644
--- a/cc/trees/layer_tree_host_unittest_damage.cc
+++ b/cc/trees/layer_tree_host_unittest_damage.cc
@@ -83,10 +83,12 @@ class LayerTreeHostDamageTestNoDamageDoesNotSwap
         // Cause visible damage.
         content_->SetNeedsDisplayRect(
             gfx::Rect(layer_tree_host()->device_viewport_size()));
+        layer_tree_host()->SetNeedsCommit();
         break;
       case 3:
         // Cause non-visible damage.
         content_->SetNeedsDisplayRect(gfx::Rect(1990, 1990, 10, 10));
+        layer_tree_host()->SetNeedsCommit();
         break;
     }
   }