Implement initialization for GDataCache to use in-memory metadata for tests.

chrome/browser/chromeos/gdata/gdata_file_system_unittest.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 <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 239 matching lines @@
                                        mock_webapps_registry_.get(),
                                        blocking_task_runner_);
 
     mock_cache_observer_.reset(new StrictMock<MockGDataCacheObserver>);
     cache_->AddObserver(mock_cache_observer_.get());
 
     mock_directory_observer_.reset(new StrictMock<MockDirectoryChangeObserver>);
     file_system_->AddObserver(mock_directory_observer_.get());
 
     file_system_->Initialize();
-    cache_->RequestInitializeOnUIThread();
+    cache_->RequestInitializeOnUIThreadForTesting();
     test_util::RunBlockingPoolTask();
   }
 
   virtual void TearDown() OVERRIDE {
     ASSERT_TRUE(file_system_);
     EXPECT_CALL(*mock_doc_service_, CancelAll()).Times(1);
     delete file_system_;
     file_system_ = NULL;
     delete mock_doc_service_;
     mock_doc_service_ = NULL;
@@ skipping 2346 matching lines @@
 
   // Try to close the same file twice.
   file_system_->CloseFile(kFileInRoot, close_file_callback);
   message_loop_.Run();
 
   // It must fail.
   EXPECT_EQ(GDATA_FILE_ERROR_NOT_FOUND, callback_helper_->last_error_);
 }
 
 }   // namespace gdata