Pepper: Add append support to FileIO.

ppapi/api/ppb_file_io.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 API to create a file i/o object.
  */
 
 [generate_thunk]
 
 label Chrome {
   M14 = 1.0,
-  M25 = 1.1
+  M25 = 1.1,
+  M29 = 1.2
 };
 
 /**
  * The PP_FileOpenFlags enum contains file open constants.
  */
 [assert_size(4)]
  enum PP_FileOpenFlags {
   /** Requests read access to a file. */
   PP_FILEOPENFLAG_READ      = 1 << 0,
 
   /**
    * Requests write access to a file.  May be combined with
    * <code>PP_FILEOPENFLAG_READ</code> to request read and write access.
    */
   PP_FILEOPENFLAG_WRITE     = 1 << 1,
 
   /**
    * Requests that the file be created if it does not exist.  If the file
    * already exists, then this flag is ignored unless
    * <code>PP_FILEOPENFLAG_EXCLUSIVE</code> was also specified, in which case
    * FileIO::Open() will fail.
    */
   PP_FILEOPENFLAG_CREATE    = 1 << 2,
 
   /**
    * Requests that the file be truncated to length 0 if it exists and is a
    * regular file. <code>PP_FILEOPENFLAG_WRITE</code> must also be specified.
    */
-   PP_FILEOPENFLAG_TRUNCATE  = 1 << 3,
+  PP_FILEOPENFLAG_TRUNCATE  = 1 << 3,
 
   /**
    * Requests that the file is created when this flag is combined with
    * <code>PP_FILEOPENFLAG_CREATE</code>.  If this flag is specified, and the
    * file already exists, then the FileIO::Open() call will fail.
    */
-  PP_FILEOPENFLAG_EXCLUSIVE = 1 << 4
+  PP_FILEOPENFLAG_EXCLUSIVE = 1 << 4,
+
+ /**
+  * Requests write access to a file, but writes will always occur at the end of
+  * the file. Mututally exclusive with <code>PP_FILEOPENFLAG_WRITE</code>.
+  *
+  * This is only supported in version 1.2 (M29) and later.

[dmichael (off chromium), 2013/06/11 21:18:29]

M29 probably doesn't mean anything to most plugin or NaCl developers. I'd say
Chrome 29.

+  */
+  [version=1.2]
+  PP_FILEOPENFLAG_APPEND = 1 << 5
 };
 
 
 /**
  * The <code>PPB_FileIO</code> struct is used to operate on a regular file
  * (PP_FileType_Regular).
  */
 interface PPB_FileIO {
   /**
    * Create() creates a new FileIO object.
@@ skipping 206 matching lines @@
    * cannot be interleaved with other operations.
    */
   [version = 1.1]
   int32_t ReadToArray([in] PP_Resource file_io,
                       [in] int64_t offset,
                       [in] int32_t max_read_length,
                       [inout] PP_ArrayOutput output,
                       [in] PP_CompletionCallback callback);
 };