Avoid memory allocation for PPB_FileIO Read when callback is blocking.

ppapi/c/pp_array_output.h

 /* 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.
  */
 
-/* From pp_array_output.idl modified Thu Mar 28 11:07:53 2013. */
+/* From pp_array_output.idl modified Tue Oct 22 15:09:25 2013. */
 
 #ifndef PPAPI_C_PP_ARRAY_OUTPUT_H_
 #define PPAPI_C_PP_ARRAY_OUTPUT_H_
 
 #include "ppapi/c/pp_macros.h"
 #include "ppapi/c/pp_stdint.h"
 
 /**
  * @file
  * PP_ArrayOutput_GetDataBuffer is a callback function to allocate plugin
@@ skipping 19 matching lines @@
  * @param user_data The pointer provided in the PP_ArrayOutput structure. This
  * has no meaning to the browser, it is intended to be used by the
  * implementation to figure out where to put the data.
  *
  * @param element_count The number of elements in the array. This will be 0
  * if there is no data to return.
  *
  * @param element_size The size of each element in bytes.
  *
  * @return Returns a pointer to the allocated memory. On failure, returns null.
- * You can also return null if the element_count is 0.
+ * You can also return null if the element_count is 0. When a non-null value is
+ * returned, the buffer must remain valid until after the callback runs. If used
+ * with a blocking callback, the buffer must remain valid until after the
+ * function returns. The plugin can then free any memory that it allocated.
  */
 
 
 /**
  * @addtogroup Typedefs
  * @{
  */
 typedef void* (*PP_ArrayOutput_GetDataBuffer)(void* user_data,
                                               uint32_t element_count,
                                               uint32_t element_size);
@@ skipping 35 matching lines @@
  * }
  * void MyFunction() {
  *   MyArrayOutput array = { NULL, 0 };
  *   PP_ArrayOutput output = { &MyGetDataBuffer, &array };
  *   ppb_foo->GetData(&output);
  * }
  * @endcode
  */
 struct PP_ArrayOutput {
   /**
-   * A pointer to the allocation function that the browser implements.
+   * A pointer to the allocation function that the browser will call.
    */
   PP_ArrayOutput_GetDataBuffer GetDataBuffer;
   /**
    * Data that is passed to the allocation function. Typically, this is used
    * to communicate how the data should be stored.
    */
   void* user_data;
 };
 /**
  * @}
  */
 
 #endif  /* PPAPI_C_PP_ARRAY_OUTPUT_H_ */