Add callback documentation to some pubsub methods.

lib/pubsub/index.js

@@ -103,6 +103,12 @@ function PubSub(options) {
  * @param {string=} query.pageToken - Page token.
  * @param {number=} query.pageSize - Max number of results to return.
  * @param {function} callback - The callback function.
+ * @param {?error} callback.err - An error from the API call, may be null.
+ * @param {module:pubsub/topic[]} callback.topics - The list of topics returned.
+ * @param {object} callback.nextQuery - A query object representing the next
+ *     page of topics.
+ * @param {object} callback.apiResponse - The full API response from the
+ *     service.
  *
  * @example
  * // Get all topics.
@@ -147,6 +153,10 @@ PubSub.prototype.getTopics = function(query, callback) {
  *
  * @param {string} name - Name of the topic.
  * @param {function=} callback - The callback function.
+ * @param {?error} callback.err - An error from the API call, may be null.
+ * @param {module:pubsub/topic} callback.topic - The newly created topic.
+ * @param {object} callback.apiResponse - The full API response from the
+ *     service.
  *
  * @example
  * pubsub.createTopic('my-new-topic', function(err, topic, apiResponse) {
@@ -341,6 +351,13 @@ PubSub.prototype.topic = function(name, options) {
  * @param {number} options.pageSize - Maximum number of results to return.
  * @param {string} options.pageToken - Page token.
  * @param {function} callback - The callback function.
+ * @param {?error} callback.err - An error from the API call, may be null.
+ * @param {module:pubsub/subscription[]} callback.subscriptions - The list of
+ *     subscriptions returned.
+ * @param {object} callback.nextQuery - A query object representing the next
+ *     page of topics.
+ * @param {object} callback.apiResponse - The full API response from the
+ *     service.
  *
  * @example
  * var callback = function(err, subscriptions, nextQuery, apiResponse) {