app_mode: Add runtime.onRestartRequired event.

chrome/common/extensions/api/runtime.json

Index: chrome/common/extensions/api/runtime.json
diff --git a/chrome/common/extensions/api/runtime.json b/chrome/common/extensions/api/runtime.json
index ad655e114396891b6f2bf5bd7a4161912e76bc15..bdfafddca3777110abccf23634f6b0a30859fea1 100644
--- a/chrome/common/extensions/api/runtime.json
+++ b/chrome/common/extensions/api/runtime.json
@@ -408,10 +408,20 @@
           "optional": "true",
           "description": "Return true from the event listener if you wish to call <code>sendResponse</code> after the event listener returns."
         }
+      },
+      {
+        "name": "onRestartRequired",
+        "type": "function",
+        "description": "Fired when an app or the device that it runs on needs to be restarted. The app should close all its windows at its earliest convenient time to let the restart to happen. If the app does nothing, a restart will be enforced after a 24-hour grace period has passed. Currently, this event is only fired for Chrome OS kiosk apps.",
+        "parameters": [
+          {
+            "type": "string",
+            "name": "reason",
+            "description": "The reason that the event is being dispatched.",
+            "enum": ["app_update", "os_update", "periodic"]
+          }
+        ]
       }
-
-
-
     ]
   }
 ]