Fixes compile with webkit compositor.

I think this is the correct fix, but it might be because my local git repo is in a bad state.

Review URL: http://codereview.chromium.org/8500012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110944 0039d316-1c4b-4281-b951-d872f2087c98

ui/aura/desktop.cc

@@ -184,7 +184,7 @@ Desktop::Desktop()
 Desktop::~Desktop() {
   in_destructor_ = true;
 #ifdef USE_WEBKIT_COMPOSITOR
-  if (!compositor_factory_)
+  if (!ui::Compositor::compositor_factory())
     ui::CompositorCC::Terminate();
 #endif
   if (instance_ == this)