Adds Ctrl-Shift-Q support inside AppList

ash/shell/shell_main.cc

Index: ash/shell/shell_main.cc
diff --git a/ash/shell/shell_main.cc b/ash/shell/shell_main.cc
index 4837071bfc99fd6a9a945c90aa4e79e1bc169423..e0521b39a23099d247e709b8be91b3f3717f32b5 100644
--- a/ash/shell/shell_main.cc
+++ b/ash/shell/shell_main.cc
@@ -58,6 +58,10 @@ class ShellDelegateImpl : public ash::ShellDelegate {
     return ash::internal::CreateStatusArea();
   }
 
+  virtual void Exit() OVERRIDE {
+    MessageLoopForUI::current()->Quit();
+  }
+
   virtual void BuildAppListModel(ash::AppListModel* model) OVERRIDE {
     ash::shell::BuildAppListModel(model);
   }