Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/ui/views/frame/browser_view.cc

Index: chrome/browser/ui/views/frame/browser_view.cc
diff --git a/chrome/browser/ui/views/frame/browser_view.cc b/chrome/browser/ui/views/frame/browser_view.cc
index 26a7a7b69e4a76a025c6a1c487303661e7d23590..4cbd7e242eff39c35b07ce9322c4ad0168e93539 100644
--- a/chrome/browser/ui/views/frame/browser_view.cc
+++ b/chrome/browser/ui/views/frame/browser_view.cc
@@ -644,13 +644,13 @@ bool BrowserView::GetAccelerator(int cmd_id, menus::Accelerator* accelerator) {
 
 bool BrowserView::ActivateAppModalDialog() const {
   // If another browser is app modal, flash and activate the modal browser.
-  if (Singleton<AppModalDialogQueue>()->HasActiveDialog()) {
+  if (AppModalDialogQueue::GetInstance()->HasActiveDialog()) {
     Browser* active_browser = BrowserList::GetLastActive();
     if (active_browser && (browser_ != active_browser)) {
       active_browser->window()->FlashFrame();
       active_browser->window()->Activate();
     }
-    Singleton<AppModalDialogQueue>()->ActivateModalDialog();
+    AppModalDialogQueue::GetInstance()->ActivateModalDialog();
     return true;
   }
   return false;