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

extensions/common/api/runtime.json

Index: extensions/common/api/runtime.json
diff --git a/extensions/common/api/runtime.json b/extensions/common/api/runtime.json
index c36c6c74879cf842697679a63fe10fed255c36a1..f466fe4d15fbff5905bf9e6bc03ca4de5531c6c6 100644
--- a/extensions/common/api/runtime.json
+++ b/extensions/common/api/runtime.json
@@ -264,6 +264,36 @@
         "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,