Require a user gesture to display the PPAPI file chooser

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 93 matching lines @@
    */
   PP_ERROR_FILECHANGED    = -23,
   /** This value indicates failure due to a time limit being exceeded. */
   PP_ERROR_TIMEDOUT       = -30,
   /**
    * This value indicates that the user cancelled rather than providing
    * expected input.
    */
   PP_ERROR_USERCANCEL     = -40,
   /**
+   * This value indicates failure due to lack of a user gesture such as a
+   * mouse click or key input event. Examples of actions requiring a user
+   * gesture are showing the file chooser dialog and going into fullscreen
+   * mode.
+   */
+  PP_ERROR_NO_USER_GESTURE = -41,
+  /**
    * This value indicates that the graphics context was lost due to a
    * power management event.
    */
   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
 };