PPAPI: Make blocking completion callbacks work.

ppapi/thunk/ppb_file_io_trusted_thunk.cc

 // 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.
 
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/trusted/ppb_file_io_trusted.h"
 #include "ppapi/thunk/enter.h"
 #include "ppapi/thunk/thunk.h"
 #include "ppapi/thunk/ppb_file_io_api.h"
 #include "ppapi/thunk/resource_creation_api.h"
 
 namespace ppapi {
 namespace thunk {
 
 namespace {
 
 typedef EnterResource<PPB_FileIO_API> EnterFileIO;
 
 int32_t GetOSFileDescriptor(PP_Resource file_io) {
   EnterFileIO enter(file_io, true);
   if (enter.failed())
     return enter.retval();
-  return enter.SetResult(enter.object()->GetOSFileDescriptor());

[dmichael (off chromium), 2012/04/19 20:02:00]

With no callback, it doesn't make sense to call SetResult (I added a DCHECK just
to make things clearer, since SetResult is complicated enough without this
support, I'd rather just not allow calls to SetResult when it doesn't really do
anything.

+  return enter.object()->GetOSFileDescriptor();
 }
 
 int32_t WillWrite(PP_Resource file_io,
                   int64_t offset,
                   int32_t bytes_to_write,
                   PP_CompletionCallback callback) {
   EnterFileIO enter(file_io, callback, true);
   if (enter.failed())
     return enter.retval();
   return enter.SetResult(enter.object()->WillWrite(offset, bytes_to_write,
-                                                   callback));
+                                                   enter.callback()));
 }
 
 int32_t WillSetLength(PP_Resource file_io,
                       int64_t length,
                       PP_CompletionCallback callback) {
   EnterFileIO enter(file_io, callback, true);
   if (enter.failed())
     return enter.retval();
-  return enter.SetResult(enter.object()->WillSetLength(length, callback));
+  return enter.SetResult(enter.object()->WillSetLength(length,
+                                                       enter.callback()));
 }
 
 const PPB_FileIOTrusted g_ppb_file_io_trusted_thunk = {
   &GetOSFileDescriptor,
   &WillWrite,
   &WillSetLength
 };
 
 }  // namespace
 
 const PPB_FileIOTrusted_0_4* GetPPB_FileIOTrusted_0_4_Thunk() {
   return &g_ppb_file_io_trusted_thunk;
 }
 
 }  // namespace thunk
 }  // namespace ppapi