Pepper: Fix the definition of |PPB_AudioInput_Callback|.

ppapi/api/dev/ppb_audio_input_dev.idl

 /* Copyright (c) 2011 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_AudioInput_Dev</code> interface, which
  * provides realtime audio input capture.
  */
 
 label Chrome {
   M17 = 0.1
 };
 
 /**
  * <code>PPB_AudioInput_Callback</code> defines the type of an audio callback
  * function used to provide the audio buffer with data. This callback will be
- * called on a separate thread to the creation thread.
+ * called on a separate thread from the creation thread.
  */
-typedef void PPB_AudioInput_Callback([out] mem_t sample_buffer,
+typedef void PPB_AudioInput_Callback([in] mem_t sample_buffer,
                                      [in] uint32_t buffer_size_in_bytes,
                                      [inout] mem_t user_data);
 
 /**
  * The <code>PPB_AudioInput_Dev</code> interface contains pointers to several
  * functions for handling audio input resources.
  */
 [version=0.1, macro="PPB_AUDIO_INPUT_DEV_INTERFACE"]
 interface PPB_AudioInput_Dev {
   /**
@@ skipping 54 matching lines @@
    *
    * @return A PP_BOOL containing PP_TRUE if successful, otherwise PP_FALSE.
    * Also returns PP_TRUE (and is a no-op) if called while capture is already
    * stopped. If a buffer is being captured, StopCapture will block until the
    * call completes.
    */
   PP_Bool StopCapture(
       [in] PP_Resource audio_input);
 };