Encrypted Media: Allows empty key message to be fired.

ppapi/api/private/ppb_content_decryptor_private.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 the <code>PPB_ContentDecryptor_Private</code>
  * interface. Note: This is a special interface, only to be used for Content
  * Decryption Modules, not normal plugins.
  */
@@ skipping 76 matching lines @@
    * <code>AddKey()</code> and <code>KeyMessage()</code> calls required to
    * prepare for decryption.
    *
    * @param[in] key_system A <code>PP_Var</code> of type
    * <code>PP_VARTYPE_STRING</code> containing the name of the key system.
    *
    * @param[in] session_id A <code>PP_Var</code> of type
    * <code>PP_VARTYPE_STRING</code> containing the session ID.
    *
    * @param[in] resource A <code>PP_Resource</code> corresponding to a
-   * <code>PPB_Buffer_Dev</code> resource that contains the message.
+   * <code>PPB_Buffer_Dev</code> resource that contains the message. A 0
+   * resource is allowed which indicates an empty message.
    *
    * @param[in] default_url A <code>PP_Var</code> of type
    * <code>PP_VARTYPE_STRING</code> containing the default URL for the message.
    */
   void KeyMessage(
       [in] PP_Instance instance,
       [in] PP_Var key_system,
       [in] PP_Var session_id,
       [in] PP_Resource message,
       [in] PP_Var default_url);
@@ skipping 134 matching lines @@
    *
    * @param[in] decrypted_block_info A <code>PP_DecryptedBlockInfo</code> that
    * contains the tracking info and result code associated with the
    * <code>decrypted_block</code>.
    */
   void DeliverSamples(
       [in] PP_Instance instance,
       [in] PP_Resource audio_frames,
       [in] PP_DecryptedBlockInfo decrypted_block_info);
 };