[Sync] Move sessions files from sync_driver to sync_sessions.

The sync team has decided that datatype specific code should no longer
live in sync_driver. //c/sync_driver will conceptually be at the same
level as //sync in the dependency tree, with datatype logic living in
special components such as sync_sessions or the datatype components
themselves.

BUG=543199
TBR=jam

Review URL: https://codereview.chromium.org/1443453002

Cr-Commit-Position: refs/heads/master@{#359886}

diff --git a/components/sync_sessions/open_tabs_ui_delegate.cc b/components/sync_sessions/open_tabs_ui_delegate.cc
new file mode 100644
index 0000000..9943d0c
--- /dev/null
+++ b/components/sync_sessions/open_tabs_ui_delegate.cc

@@ -0,0 +1,11 @@
+// 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.
+
+#include "components/sync_sessions/open_tabs_ui_delegate.h"
+
+namespace sync_driver {
+
+OpenTabsUIDelegate::~OpenTabsUIDelegate() {}
+
+}  // namespace sync_driver