Add API definition and error values for running message loops.

ppapi/api/pp_errors.idl

 /* Copyright (c) 2012 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.
  */
 
 /**
  * This file defines an enumeration of all PPAPI error codes.
  */
 
 /**
@@ skipping 96 matching lines @@
   PP_ERROR_TIMEDOUT       = -30,
   /**
    * This value indicates that the user cancelled rather than providing
    * expected input.
    */
   PP_ERROR_USERCANCEL     = -40,
   /**
    * This value indicates that the graphics context was lost due to a
    * power management event.
    */
-  PP_ERROR_CONTEXT_LOST = -50
+  PP_ERROR_CONTEXT_LOST   = -50,
+  /**
+   * Indicates an attempt to make a PPAPI call on a thread without previously
+   * registering a message loop via PPB_MessageLoop.AttachToCurrentThread.
+   * Without this registration step, no PPAPI calls are supported.
+   */
+  PP_ERROR_NO_MESSAGE_LOOP = -51,
+  /**
+   * Indicates that the requested operation is not permitted on the current
+   * thread.
+   */
+  PP_ERROR_WRONG_THREAD   = -52
 };