Aura: Make compositor_unittests work with --ui-enable-threaded-compositing

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 92b52da35ba2779d329faa937d4333edb5db2467..f3a3c8bd74c6830c0db843127f5beefd70db0e18 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -474,6 +474,7 @@ Compositor::~Compositor() {
   ContextFactory::GetInstance()->RemoveCompositor(this);
 }
 
+// static
 void Compositor::Initialize(bool use_thread) {
   if (use_thread) {
     g_compositor_thread = new base::Thread("Browser Compositor");
@@ -481,6 +482,12 @@ void Compositor::Initialize(bool use_thread) {
   }
 }
 
+// static
+bool Compositor::WasInitializedWithThread() {
+  return !!g_compositor_thread;
+}
+
+// static
 void Compositor::Terminate() {
   if (g_compositor_thread) {
     g_compositor_thread->Stop();