Add a new app API to enable watchdog behavior restarts in kiosk apps

extensions/common/api/runtime.json

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Note: Many of these functions and events are implemented by hand and should
 // not elicit any code generation from the schema compiler. These items are
 // marked "nocompile."
 [
   {
     "namespace": "runtime",
@@ skipping 246 matching lines @@
           }
         ]
       },
       {
         "name": "restart",
         "description": "Restart the ChromeOS device when the app runs in kiosk mode. Otherwise, it's no-op.",
         "type": "function",
         "parameters": []
       },
       {
+        "name": "restartOnWatchdog",
+        "description": "Restart the ChromeOS device when the app runs in kiosk mode after the given seconds. If called again before the time ends, the reboot will be delayed. If called with a value of -1, the reboot will be cancelled. It's a no-op in non-kiosk mode. It's only allowed to be called repeatedly by the first extension to invoke this API.",
+        "type": "function",
+        "parameters": [
+          {
+            "type": "integer",
+            "name": "seconds",
+            "description": "Time to wait in seconds before rebooting the device, or -1 to cancel a scheduled reboot."
+          },
+          {
+            "type": "function",
+            "name": "onWatchdogTimeoutCallback",
+            "description": "A callback to be invoked when a scheduled restart attempt is executed or when an immediate status is sent to the caller, like failure or success to cancel any previously scheduled restarts.",
+            "optional": true,
+            "parameters": [
+              {
+                "name": "success",

[Devlin, 2016/05/20 17:26:33]

For consistency, success should be indicated by whether or not lastError is set,
not by a separate return result.

[afakhry, 2016/05/21 01:13:00]

I'm sorry, I don't get this comment. Not sure which lastError or which separate
return result?

[Devlin, 2016/05/23 16:49:39]

chrome.runtime.lastError is used to indicate whether an api call succeeded or
failed, and is the canonical way of indicating success/failure in an API method.
 Here, you're returning a separate parameter ('success') to indicate it.  We
shouldn't deviate from established patterns.

[afakhry, 2016/05/25 01:55:46]

Done.

+                "type": "boolean",
+                "description": "Status of the request. True when the restart attempt is successful or when a previously scheduled restart was cancled by calling this API with seconds = -1. False otherwise."
+              },
+              {
+                "name": "message",
+                "type": "string",
+                "description": "Status message of the request."
+              }
+            ]
+          }
+        ]
+      },
+      {
         "name": "connect",
         "type": "function",
         "nocompile": true,
         "description": "Attempts to connect to connect listeners within an extension/app (such as the background page), or other extensions/apps. This is useful for content scripts connecting to their extension processes, inter-app/extension communication, and <a href=\"manifest/externally_connectable.html\">web messaging</a>. Note that this does not connect to any listeners in a content script. Extensions may connect to content scripts embedded in tabs via $(ref:tabs.connect).",
         "parameters": [
           {"type": "string", "name": "extensionId", "optional": true, "description": "The ID of the extension or app to connect to. If omitted, a connection will be attempted with your own extension. Required if sending messages from a web page for <a href=\"manifest/externally_connectable.html\">web messaging</a>."},
           {
             "type": "object",
             "name": "connectInfo",
             "properties": {
@@ skipping 266 matching lines @@
           {
             "$ref": "OnRestartRequiredReason",
             "name": "reason",
             "description": "The reason that the event is being dispatched."
           }
         ]
       }
     ]
   }
 ]