[FileAPI] Replace default leveldb::Env with leveldb::MemEnv in tests.

chrome/browser/sync_file_system/local/local_file_change_tracker.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_
 
 #include <deque>
 #include <map>
 #include <string>
@@ skipping 11 matching lines @@
 
 namespace base {
 class SequencedTaskRunner;
 }
 
 namespace fileapi {
 class FileSystemContext;
 class FileSystemURL;
 }
 
+namespace leveldb {
+class Env;
+}
+
 namespace sync_file_system {
 
 // Tracks local file changes for cloud-backed file systems.
 // All methods must be called on the file_task_runner given to the constructor.
 // Owned by FileSystemContext.
 class LocalFileChangeTracker
     : public fileapi::FileUpdateObserver,
       public fileapi::FileChangeObserver {
  public:
   // |file_task_runner| must be the one where the observee file operations run.
   // (So that we can make sure DB operations are done before actual update
   // happens)
   LocalFileChangeTracker(const base::FilePath& base_path,
+                         leveldb::Env* env_override,
                          base::SequencedTaskRunner* file_task_runner);
   virtual ~LocalFileChangeTracker();
 
   // FileUpdateObserver overrides.
   virtual void OnStartUpdate(const fileapi::FileSystemURL& url) OVERRIDE;
   virtual void OnUpdate(
       const fileapi::FileSystemURL& url, int64 delta) OVERRIDE {}
   virtual void OnEndUpdate(const fileapi::FileSystemURL& url) OVERRIDE;
 
   // FileChangeObserver overrides.
@@ skipping 121 matching lines @@
   // This can be accessed on any threads (with num_changes_lock_).
   int64 num_changes_;
   mutable base::Lock num_changes_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalFileChangeTracker);
 };
 
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_