Adds Ctrl-Shift-Q support inside AppList

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index ff60e8ac8275ebe864aa87b45d6812496b6894db..3be69cb2460685a86b8172bfd2b7332dcd2ada30 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -56,6 +56,9 @@ class ASH_EXPORT ShellDelegate {
   // Invoked to create a new status area. Can return NULL.
   virtual views::Widget* CreateStatusArea() = 0;
 
+  // Invoked when a user uses Ctrl-Shift-Q to close chrome.
+  virtual void Exit() = 0;
+
   // Invoked to ask the delegate to populate the |model|.
   virtual void BuildAppListModel(AppListModel* model) = 0;