[Sync] Fixing easy lint violations.

components/sync_sessions/synced_session_tracker.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 "components/sync_sessions/synced_session_tracker.h"
 
+#include <utility>
+
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/sync_sessions/sync_sessions_client.h"
 
 namespace sync_sessions {
 
 namespace {
 
 // Helper for iterating through all tabs within a window, and all navigations
@@ skipping 330 matching lines @@
 
   // Get rid of our convenience maps (does not delete the actual Window/Tabs
   // themselves; they should have all been deleted above).
   synced_window_map_.clear();
   synced_tab_map_.clear();
 
   local_session_tag_.clear();
 }
 
 }  // namespace sync_sessions