Add chrome://quit to shut down Chrome, including packaged apps.

chrome/browser/browser_about_handler.cc

Index: chrome/browser/browser_about_handler.cc
diff --git a/chrome/browser/browser_about_handler.cc b/chrome/browser/browser_about_handler.cc
index df8d739de06ab58987f37cb8ff81cd9b501c9f45..1197f049068db7abe3190a811ea3f6de42fcf06c 100644
--- a/chrome/browser/browser_about_handler.cc
+++ b/chrome/browser/browser_about_handler.cc
@@ -70,6 +70,9 @@ bool WillHandleBrowserAboutURL(GURL* url,
     // gtk objects after they are destoyed by BrowserWindowGtk::Close().
     base::MessageLoop::current()->PostTask(FROM_HERE,
         base::Bind(&chrome::AttemptRestart));
+  } else if (host == chrome::kChromeUIQuitHost) {
+    base::MessageLoop::current()->PostTask(FROM_HERE,
+        base::Bind(&chrome::AttemptExit));
   }
 
   GURL::Replacements replacements;