Implement first part of supporting global extension commands.

ui/gfx/win/singleton_hwnd.cc

Index: ui/gfx/win/singleton_hwnd.cc
diff --git a/ui/gfx/win/singleton_hwnd.cc b/ui/gfx/win/singleton_hwnd.cc
index 37993e8f4f0fc05ec40fdca05020e6d55fef9a2d..c24579d2f6a8f3520c41eff542255a89ef265301 100644
--- a/ui/gfx/win/singleton_hwnd.cc
+++ b/ui/gfx/win/singleton_hwnd.cc
@@ -14,17 +14,20 @@ SingletonHwnd* SingletonHwnd::GetInstance() {
   return Singleton<SingletonHwnd>::get();
 }
 
-void SingletonHwnd::AddObserver(Observer* observer) {
-  if (!hwnd()) {
-    if (!base::MessageLoop::current() ||
-        base::MessageLoop::current()->type() != base::MessageLoop::TYPE_UI) {
-      // Creating this window in (e.g.) a renderer inhibits shutdown on
-      // Windows. See http://crbug.com/230122 and http://crbug.com/236039.
-      DLOG(ERROR) << "Cannot create windows on non-UI thread!";
-      return;
-    }
-    WindowImpl::Init(NULL, Rect());
+void SingletonHwnd::Init() {
+  if (!base::MessageLoop::current() ||
+      base::MessageLoop::current()->type() != base::MessageLoop::TYPE_UI) {
+    // Creating this window in (e.g.) a renderer inhibits shutdown on
+    // Windows. See http://crbug.com/230122 and http://crbug.com/236039.
+    DLOG(ERROR) << "Cannot create windows on non-UI thread!";
+    return;
   }
+  WindowImpl::Init(NULL, Rect());
+}
+
+void SingletonHwnd::AddObserver(Observer* observer) {
+  if (!hwnd())
+    Init();
   observer_list_.AddObserver(observer);
 }