Move ImportantFileWriter to base/. It now has two consumers, base/prefs and chrome/.

base/files/important_file_writer.h

 // 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.
 
-#ifndef CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
-#define CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
+#ifndef BASE_FILES_IMPORTANT_FILE_WRITER_H_
+#define BASE_FILES_IMPORTANT_FILE_WRITER_H_
 
 #include <string>
 
+#include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time.h"
 #include "base/timer.h"
 
 namespace base {
+
 class MessageLoopProxy;
 class Thread;
-}
 
 // Helper to ensure that a file won't be corrupted by the write (for example on
 // application crash). Consider a naive way to save an important file F:
 //
 // 1. Open F for writing, truncating it.
 // 2. Write new data to F.
 //
 // It's good when it works, but it gets very bad if step 2. doesn't complete.
 // It can be caused by a crash, a computer hang, or a weird I/O error. And you
 // end up with a broken file.
 //
 // To be safe, we don't start with writing directly to F. Instead, we write to
 // to a temporary file. Only after that write is successful, we rename the
 // temporary file to target filename.
 //
 // If you want to know more about this approach and ext3/ext4 fsync issues, see
 // http://valhenson.livejournal.com/37921.html
-class ImportantFileWriter : public base::NonThreadSafe {
+class BASE_EXPORT ImportantFileWriter : public NonThreadSafe {
  public:
   // Used by ScheduleSave to lazily provide the data to be saved. Allows us
   // to also batch data serializations.
   class DataSerializer {
    public:
     // Should put serialized string in |data| and return true on successful
     // serialization. Will be called on the same thread on which
     // ImportantFileWriter has been created.
     virtual bool SerializeData(std::string* data) = 0;
 
    protected:
     virtual ~DataSerializer() {}
   };
 
   // Initialize the writer.
   // |path| is the name of file to write.
   // |file_message_loop_proxy| is the MessageLoopProxy for a thread on which
   // file I/O can be done.
   // All non-const methods, ctor and dtor must be called on the same thread.
   ImportantFileWriter(const FilePath& path,
-                      base::MessageLoopProxy* file_message_loop_proxy);
+                      MessageLoopProxy* file_message_loop_proxy);
 
   // You have to ensure that there are no pending writes at the moment
   // of destruction.
   ~ImportantFileWriter();
 
   const FilePath& path() const { return path_; }
 
   // Returns true if there is a scheduled write pending which has not yet
   // been started.
   bool HasPendingWrite() const;
 
   // Save |data| to target filename. Does not block. If there is a pending write
   // scheduled by ScheduleWrite, it is cancelled.
   void WriteNow(const std::string& data);
 
   // Schedule a save to target filename. Data will be serialized and saved
   // to disk after the commit interval. If another ScheduleWrite is issued
   // before that, only one serialization and write to disk will happen, and
   // the most recent |serializer| will be used. This operation does not block.
   // |serializer| should remain valid through the lifetime of
   // ImportantFileWriter.
   void ScheduleWrite(DataSerializer* serializer);
 
   // Serialize data pending to be saved and execute write on backend thread.
   void DoScheduledWrite();
 
-  base::TimeDelta commit_interval() const {
+  TimeDelta commit_interval() const {
     return commit_interval_;
   }
 
-  void set_commit_interval(const base::TimeDelta& interval) {
+  void set_commit_interval(const TimeDelta& interval) {
     commit_interval_ = interval;
   }
 
  private:
   // Path being written to.
   const FilePath path_;
 
   // MessageLoopProxy for the thread on which file I/O can be done.
-  scoped_refptr<base::MessageLoopProxy> file_message_loop_proxy_;
+  scoped_refptr<MessageLoopProxy> file_message_loop_proxy_;
 
   // Timer used to schedule commit after ScheduleWrite.
-  base::OneShotTimer<ImportantFileWriter> timer_;
+  OneShotTimer<ImportantFileWriter> timer_;
 
   // Serializer which will provide the data to be saved.
   DataSerializer* serializer_;
 
   // Time delta after which scheduled data will be written to disk.
-  base::TimeDelta commit_interval_;
+  TimeDelta commit_interval_;
 
   DISALLOW_COPY_AND_ASSIGN(ImportantFileWriter);
 };
 
-#endif  // CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
+}  // namespace base
+
+#endif  // BASE_FILES_IMPORTANT_FILE_WRITER_H_