Avoid memory allocation for PPB_FileIO Read when callback is blocking.

ppapi/c/pp_array_output.h

Index: ppapi/c/pp_array_output.h
diff --git a/ppapi/c/pp_array_output.h b/ppapi/c/pp_array_output.h
index add873cf8d1b9f32052a271c3276edadd2ba7337..2d9a174bd3c9b63e8878cf338a728031ee3aeb6e 100644
--- a/ppapi/c/pp_array_output.h
+++ b/ppapi/c/pp_array_output.h
@@ -3,7 +3,7 @@
  * 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 13:40:12 2013. */
 
 #ifndef PPAPI_C_PP_ARRAY_OUTPUT_H_
 #define PPAPI_C_PP_ARRAY_OUTPUT_H_
@@ -43,7 +43,10 @@
  * @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. If memory is allocated on
+ * the heap, the plugin is responsible for freeing it after the callback runs.
+ * If used with a blocking callback, the memory must remain valid until the
+ * callback runs even if the plugin causes the operation to abort.
  */