Moved JsonPrefStore to use SequencedWorkerPool

chrome/common/important_file_writer.h

Index: chrome/common/important_file_writer.h
diff --git a/chrome/common/important_file_writer.h b/chrome/common/important_file_writer.h
index 5bd5deff44bac68c517da7f62495508aa5b10844..bb8847880f813a91be1c484a66e4a81a00c97b4b 100644
--- a/chrome/common/important_file_writer.h
+++ b/chrome/common/important_file_writer.h
@@ -15,7 +15,7 @@
 #include "base/timer.h"
 
 namespace base {
-class MessageLoopProxy;
+class SequencedTaskRunner;
 class Thread;
 }
 
@@ -52,11 +52,11 @@ class ImportantFileWriter : public base::NonThreadSafe {
 
   // 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.
+  // |task_runner| is the SequencedTaskRunner instance where on which we will
+  // execute file I/O operations.
   // All non-const methods, ctor and dtor must be called on the same thread.
   ImportantFileWriter(const FilePath& path,
-                      base::MessageLoopProxy* file_message_loop_proxy);
+                      base::SequencedTaskRunner* task_runner);
 
   // You have to ensure that there are no pending writes at the moment
   // of destruction.
@@ -95,8 +95,8 @@ class ImportantFileWriter : public base::NonThreadSafe {
   // 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_;
+  // TaskRunner for the thread on which file I/O can be done.
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   // Timer used to schedule commit after ScheduleWrite.
   base::OneShotTimer<ImportantFileWriter> timer_;