[GCM] API update to allow only a single sender in registration

chrome/common/extensions/api/gcm.json

 // Copyright 2013 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.
 
 [
   {
     "namespace": "gcm",
     "description": "Use <code>chrome.gcm</code> to enable apps and extensions to send and receive messages through <a href='http://developer.android.com/google/gcm/index.html'>Google Cloud Messaging for Android</a>.",
     "properties": {
       "MAX_MESSAGE_SIZE": {
         "value": 4096,
         "description": "The maximum size (in bytes) of all key/value pairs in a message."
       }
     },
     "functions": [
       {
         "name": "register",
         "type": "function",
-        "description": "Registers the application with GCM. The registration ID will be returned by the <code>callback</code>. If <code>register</code> is called again with the same list of <code>senderIds</code>, the same registration ID will be returned.",
+        "description": "Registers the application with GCM. The registration ID will be returned by the <code>callback</code>.",

[not at google - send to devlin, 2014/02/28 22:36:48]

The comment you removed explained what happened when the call is made multiple
times. Could you add something like that here?

[fgorski, 2014/03/03 23:14:16]

Done. I've brought the statement back adjusted for the "arity" of sender Id.
I'll update the documentation further once we land cloudMessagingV2
doc.(together with other updates based on API review)

         "parameters": [
           {
-            "name": "senderIds",
-            "type": "array",
-            "items": { 
-              "type": "string",
-              "minLength": 1
-            },
-            "minItems": 1,
-            "maxItems": 100,
+            "name": "senderId",
+            "type": "string",
+            "minLength": 1,
             "description": "A list of server IDs that are allowed to send messages to the application. It should contain at least one and no more than 100 sender IDs."

[not at google - send to devlin, 2014/02/28 22:36:48]

This description needs an overhaul.

[fgorski, 2014/03/03 23:14:16]

Done.

           },
           {
             "name": "callback",
             "type": "function",
             "description": "Function called when registration completes. It should check $(ref:runtime.lastError) for error when <code>registrationId</code> is empty.",
             "parameters": [
-              { 
+              {
                 "name": "registrationId",
                 "type": "string",
                 "description": "A registration ID assigned to the application by the GCM."
               }
             ]
           }
         ]
       },
       {
         "name": "send",
@@ skipping 104 matching lines @@
                 "description": "Additional details related to the error, when available."
               }
             },
             "description": "An error that occured while trying to send the message either in Chrome or on the GCM server. Application can retry sending the message with a reasonable backoff and possibly longer time-to-live."
           }
         ]
       }
     ]
   }
 ]