app_shell: Extend identity API stub

extensions/shell/common/api/identity.idl

Index: extensions/shell/common/api/identity.idl
diff --git a/extensions/shell/common/api/identity.idl b/extensions/shell/common/api/identity.idl
index a77509a9e4512eb0d11b279bbe14758b88bbe7f2..f5e681e9b6f8d49a9b1122cc74768b4cd4cab27f 100644
--- a/extensions/shell/common/api/identity.idl
+++ b/extensions/shell/common/api/identity.idl
@@ -10,14 +10,31 @@ namespace identity {
     boolean? interactive;
   };
 
+  dictionary InvalidTokenDetails {
+    // Ignored parameter. Exists only for compatibility.
+    DOMString? token;
+  };
+
   // Called with the OAuth2 access token on success or undefined on error.
   callback GetAuthTokenCallback = void (optional DOMString token);
+  
+  // Called by removeCachedAuthToken().
+  callback InvalidateAuthTokenCallback = void ();
 
   interface Functions {
     // Returns an OAuth2 access token for the current app_shell user for scopes
     // from the manifest. Does not prompt the user. 
     static void getAuthToken(GetAuthTokenDetails options,
                              GetAuthTokenCallback callback);
+
+    // Stub. Calls callback immediately because app_shell does not cache access
+    // tokens the way Chrome does.
+    static void removeCachedAuthToken(InvalidTokenDetails details,
+                                      InvalidateAuthTokenCallback callback);
   };
 
+  interface Events {
+    // Stub. Never fired because app_shell only supports a single user account.
+    static void onSignInChanged(object account, boolean signedIn);
+  };
 };