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

chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h

Index: chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h
diff --git a/chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h b/chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h
index b1b221bb428dc902253d268b69622582dafdce19..93f0da5ddc279f1c66059700ba2d219f1e92a4a9 100644
--- a/chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h
+++ b/chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h
@@ -16,6 +16,9 @@
 // This class is a singleton.
 class AppModalDialogQueue {
  public:
+  // Returns the singleton instance.
+  static AppModalDialogQueue* GetInstance();
+
   // Adds a modal dialog to the queue, if there are no other dialogs in the
   // queue, the dialog will be shown immediately. Once it is shown, the
   // most recently active browser window (or whichever is currently active)