Replace "nested message loop" with "nested run loop" in comments.

ppapi/api/ppb_message_loop.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.
  */
 
 /**
  * Defines the PPB_MessageLoop interface.
  */
 label Chrome {
   M25 = 1.0
@@ skipping 164 matching lines @@
    */
   int32_t AttachToCurrentThread([in] PP_Resource message_loop);
 
   /**
    * Runs the thread message loop. Running the message loop is required for you
    * to get issued completion callbacks on the thread.
    *
    * The message loop identified by the argument must have been previously
    * successfully attached to the current thread.
    *
-   * You may not run nested message loops. Since the main thread has an
+   * You may not run nested run loops. Since the main thread has an
    * implicit message loop that the system runs, you may not call Run on the
    * main thread.
    *
    * @return
    *   - PP_OK: The message loop was successfully run. Note that on
    *     success, the message loop will only exit when you call PostQuit().
    *   - PP_ERROR_BADRESOURCE: The given message loop resource is invalid.
    *   - PP_ERROR_WRONG_THREAD: You are attempting to run a message loop that
    *     has not been successfully attached to the current thread. Call
    *     AttachToCurrentThread().
@@ skipping 66 matching lines @@
    *
    * @return
    *   - PP_OK: The request to quit was successfully posted.
    *   - PP_ERROR_BADRESOURCE: The message loop was invalid.
    *   - PP_ERROR_WRONG_THREAD: You are attempting to quit the main thread.
    *     The main thread's message loop is managed by the system and can't be
    *     quit.
    */
   int32_t PostQuit([in] PP_Resource message_loop, PP_Bool should_destroy);
 };