[ew] Add basic classes.

chrome/browser/sync_file_system/local/sync_file_system_backend.cc

Index: chrome/browser/sync_file_system/local/sync_file_system_backend.cc
diff --git a/chrome/browser/sync_file_system/local/sync_file_system_backend.cc b/chrome/browser/sync_file_system/local/sync_file_system_backend.cc
index 50e5b94701800c7dd95475675e9defa8b3fe333b..644a01a4d949523bca34f8958ecf1b7121e5f292 100644
--- a/chrome/browser/sync_file_system/local/sync_file_system_backend.cc
+++ b/chrome/browser/sync_file_system/local/sync_file_system_backend.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/sync_file_system/local/sync_file_system_backend.h"
 
+#include <string>
+
 #include "base/logging.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/sync_file_system/local/local_file_change_tracker.h"
@@ -139,6 +141,11 @@ fileapi::AsyncFileUtil* SyncFileSystemBackend::GetAsyncFileUtil(
   return GetDelegate()->file_util();
 }
 
+fileapi::WatcherManager* SyncFileSystemBackend::GetWatcherManager(
+    fileapi::FileSystemType type) {
+  return NULL;
+}
+
 fileapi::CopyOrMoveFileValidatorFactory*
 SyncFileSystemBackend::GetCopyOrMoveFileValidatorFactory(
     fileapi::FileSystemType type,