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..89925aed60754ce05f668e11a2e859098471f831 100644
--- a/extensions/common/api/runtime.json
+++ b/extensions/common/api/runtime.json
@@ -264,6 +264,26 @@
         "parameters": []
       },
       {
+        "name": "restartAfterDelay",
+        "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": "onRestartScheduledCallback",

[Devlin, 2016/06/01 21:29:15]

probably just call this "callback"

[afakhry, 2016/06/02 01:43:40]

Done.

+            "description": "A callback to be invoked when a restart request was successfully rescheduled or when an error occurs in which case runtime.lastError can be checked.",

[Devlin, 2016/06/01 21:29:15]

the second part of this ("or when an error occurs...") is probably unnecessary,
since that's true of every API.

[afakhry, 2016/06/02 01:43:40]

Done.

+            "optional": true,
+            "parameters": [

[Devlin, 2016/06/01 21:29:15]

Do we need this?  If so, put the opening and closing braces on the same line
("[]"); if not, remove.

[afakhry, 2016/06/02 01:43:40]

Done.

+            ]
+          }
+        ]
+      },
+      {
         "name": "connect",
         "type": "function",
         "nocompile": true,