[Sync] Move sessions files from sync_driver to sync_sessions.

components/sync_sessions/BUILD.gn

Index: components/sync_sessions/BUILD.gn
diff --git a/components/sync_sessions/BUILD.gn b/components/sync_sessions/BUILD.gn
index 28813356eef27d0fcf7636079894385e39a4dc2e..cffd15aaa04d0be91ba65c74800924f7368646ce 100644
--- a/components/sync_sessions/BUILD.gn
+++ b/components/sync_sessions/BUILD.gn
@@ -8,6 +8,8 @@ source_set("sync_sessions") {
     "favicon_cache.cc",
     "favicon_cache.h",
     "local_session_event_router.h",
+    "open_tabs_ui_delegate.cc",
+    "open_tabs_ui_delegate.h",
     "revisit/bookmarks_by_url_provider_impl.cc",
     "revisit/bookmarks_by_url_provider_impl.h",
     "revisit/bookmarks_page_revisit_observer.cc",
@@ -32,10 +34,17 @@ source_set("sync_sessions") {
     "sessions_sync_manager.h",
     "sync_sessions_client.cc",
     "sync_sessions_client.h",
+    "synced_session.cc",
+    "synced_session.h",
     "synced_session_tracker.cc",
     "synced_session_tracker.h",
     "synced_tab_delegate.cc",
     "synced_tab_delegate.h",
+    "synced_window_delegate.h",
+    "synced_window_delegates_getter.cc",
+    "synced_window_delegates_getter.h",
+    "tab_node_pool.cc",
+    "tab_node_pool.h",
   ]
 
   deps = [
@@ -82,6 +91,7 @@ source_set("unit_tests") {
     "revisit/typed_url_page_revisit_task_unittest.cc",
     "session_data_type_controller_unittest.cc",
     "synced_session_tracker_unittest.cc",
+    "tab_node_pool_unittest.cc",
   ]
 
   deps = [