[fsp] Pass more detailed errors to the providing extension.

chrome/browser/chromeos/file_system_provider/fileapi/provider_async_file_util_unittest.cc

 // Copyright 2014 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 "chrome/browser/chromeos/file_system_provider/fileapi/provider_async_file_util.h"
 
 #include <string>
 #include <vector>
 
 #include "base/files/file.h"
@@ skipping 117 matching lines @@
     async_file_util_.reset(new internal::ProviderAsyncFileUtil);
 
     file_system_context_ =
         content::CreateFileSystemContextForTesting(NULL, data_dir_.path());
 
     ServiceFactory::GetInstance()->SetTestingFactory(profile_, &CreateService);
     Service* service = Service::Get(profile_);  // Owned by its factory.
     service->SetFileSystemFactoryForTesting(
         base::Bind(&FakeProvidedFileSystem::Create));
 
-    const bool result = service->MountFileSystem(
+    const base::File::Error result = service->MountFileSystem(
         kExtensionId, MountOptions(kFileSystemId, "Testing File System"));
-    ASSERT_TRUE(result);
+    ASSERT_EQ(base::File::FILE_OK, result);
     const ProvidedFileSystemInfo& file_system_info =
         service->GetProvidedFileSystem(kExtensionId, kFileSystemId)
             ->GetFileSystemInfo();
     const std::string mount_point_name =
         file_system_info.mount_path().BaseName().AsUTF8Unsafe();
 
     file_url_ =
         CreateFileSystemURL(mount_point_name,
                             base::FilePath::FromUTF8Unsafe(
                                 kFakeFilePath + 1 /* No leading slash. */));
@@ skipping 266 matching lines @@
       file_url_,
       base::Bind(&EventLogger::OnCreateSnapshotFile,
                  base::Unretained(&logger)));
 
   ASSERT_TRUE(logger.result());
   EXPECT_EQ(base::File::FILE_ERROR_INVALID_OPERATION, *logger.result());
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos