Update gapi.d.ts

I am using Google+ Sign-In on one of my applications and I needed to add a couple of definitions into this file.

The update is based on https://developers.google.com/+/web/signin/reference#javascript_api.

gapi/gapi.d.ts

@@ -65,6 +65,45 @@ declare module gapi.auth {
      * @param token The token to set.
      */
     export function setToken(token: GoogleApiOAuth2TokenObject): void;
+    /**
+     * Initiates the client-side Google+ Sign-In OAuth 2.0 flow.
+     * When the method is called, the OAuth 2.0 authorization dialog is displayed to the user and when they accept, the callback function is called.
+     * @param params
+     */
+    export function signIn(params: {
+        /**
+         * Your OAuth 2.0 client ID that you obtained from the Google Developers Console.
+         */
+        clientid?: string;
+        /**
+         * Directs the sign-in button to store user and session information in a session cookie and HTML5 session storage on the user's client for the purpose of minimizing HTTP traffic and distinguishing between multiple Google accounts a user might be signed into.
+         */
+        cookiepolicy?: string;
+        /**
+         * A function in the global namespace, which is called when the sign-in button is rendered and also called after a sign-in flow completes.
+         */
+        callback?: Function;
+        /**
+         * If true, all previously granted scopes remain granted in each incremental request, for incremental authorization. The default value true is correct for most use cases; use false only if employing delegated auth, where you pass the bearer token to a less-trusted component with lower programmatic authority.
+         */
+        includegrantedscopes?: boolean;
+        /**
+         * If your app will write moments, list the full URI of the types of moments that you intend to write.
+         */
+        requestvisibleactions?: any;
+        /**
+         * The OAuth 2.0 scopes for the APIs that you would like to use as a space-delimited list.
+         */
+        scope?: any;
+        /**
+         * If you have an Android app, you can drive automatic Android downloads from your web sign-in flow.
+         */
+        apppackagename?: string;
+    }): void;
+    /**
+     * Signs a user out of your app without logging the user out of Google. This method will only work when the user is signed in with Google+ Sign-In.
+     */
+    export function signOut(): void;
 }
 
 declare module gapi.client {