Add ReadEntries interface for PPB_DirectoryReader (won't commit)

ppapi/api/dev/ppb_directory_reader_dev.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_DirectoryReader_Dev</code> interface.
  */
 
 label Chrome {
-  M13 = 0.5
+  M13 = 0.5,
+  M26 = 0.6
 };
 
 [assert_size(8)]
 struct PP_DirectoryEntry_Dev {
   PP_Resource file_ref;
   PP_FileType file_type;
 };
 
 interface PPB_DirectoryReader_Dev {
   // Creates a DirectoryReader for the given directory.  Upon success, the
@@ skipping 16 matching lines @@
   //
   //   PP_Resource reader = reader_funcs->Create(dir_ref);
   //   PP_DirectoryEntry entry = {0};
   //   while ((reader_funcs->GetNextEntry(reader, &entry,
   //                                      PP_BlockUntilComplete()) == PP_OK) &&
   //          entry->file_ref) {
   //     ProcessDirectoryEntry(entry);
   //   }
   //   core_funcs->ReleaseResource(reader);
   //
+  [deprecate=0.6]
   int32_t GetNextEntry([in] PP_Resource directory_reader,
                        [out] PP_DirectoryEntry_Dev entry,
                        [in] PP_CompletionCallback callback);

[dmichael (off chromium), 2013/01/18 17:10:18]

Since nobody is using this API right now, let's remove this function entirely
and pretend 0.5 didn't happen :-)

+
+  // Reads all entries in the directory.
+  //
+  // @param[in] directory_reader A <code>PP_Resource</code> corresponding to a
+  // directory reader resource.
+  // @param[in] output An output array which will receive
+  // <code>PP_DirectoryEntry_Dev</code> objects on success.
+  // @param[in] callback A <code>PP_CompletionCallback</code> to run on
+  // completion.
+  //
+  // @return An error code from <code>pp_errors.h</code>.
+  //
+  [version=0.6]
+  int32_t ReadEntries([in] PP_Resource directory_reader,
+                      [in] PP_ArrayOutput output,

[darin (slow to review), 2013/01/18 06:26:19]

Most operating systems don't provide APIs like this because they can take a long
time to execute and consume a large amount of memory.  Consider large
directories.  Instead, they provide APIs to progressively fetch items (e.g.,
readdir and FindNextFile).

Also, we could easily implement ReadEntries in terms of GetNextEntry, so it
seems like ReadEntries could be a helper function if applications wish to have a
simpler way to read all of the entries in a directory.  It just seems like the
core API should be more flexible.

(It could be the case that we temporarily implement GetNextEntry using a
sub-optimal IPC to fetch all entries in one go, but that could be fixed in the
future.)

+                      [in] PP_CompletionCallback callback);
 };