[Sync] Move sessions/ to engine/cycle/ and rename things to match.

components/sync/engine_impl/cycle/data_type_tracker.h

Index: components/sync/engine_impl/cycle/data_type_tracker.h
diff --git a/components/sync/sessions_impl/data_type_tracker.h b/components/sync/engine_impl/cycle/data_type_tracker.h
similarity index 95%
rename from components/sync/sessions_impl/data_type_tracker.h
rename to components/sync/engine_impl/cycle/data_type_tracker.h
index 88a7ab2c1f07ebfa8e69e7ff0dc1177fb4de5c33..9afd434a482e654302d9ff6f9423231d0ea9a89f 100644
--- a/components/sync/sessions_impl/data_type_tracker.h
+++ b/components/sync/engine_impl/cycle/data_type_tracker.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef COMPONENTS_SYNC_SESSIONS_IMPL_DATA_TYPE_TRACKER_H_
-#define COMPONENTS_SYNC_SESSIONS_IMPL_DATA_TYPE_TRACKER_H_
+#ifndef COMPONENTS_SYNC_ENGINE_IMPL_CYCLE_DATA_TYPE_TRACKER_H_
+#define COMPONENTS_SYNC_ENGINE_IMPL_CYCLE_DATA_TYPE_TRACKER_H_
 
 #include <stddef.h>
 
@@ -21,8 +21,6 @@ namespace syncer {
 
 class InvalidationInterface;
 
-namespace sessions {
-
 // A class to track the per-type scheduling data.
 class DataTypeTracker {
  public:
@@ -149,7 +147,6 @@ class DataTypeTracker {
   DISALLOW_COPY_AND_ASSIGN(DataTypeTracker);
 };
 
-}  // namespace sessions
 }  // namespace syncer
 
-#endif  // COMPONENTS_SYNC_SESSIONS_IMPL_DATA_TYPE_TRACKER_H_
+#endif  // COMPONENTS_SYNC_ENGINE_IMPL_CYCLE_DATA_TYPE_TRACKER_H_