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

components/sync/engine_impl/cycle/nudge_tracker.cc

Index: components/sync/engine_impl/cycle/nudge_tracker.cc
diff --git a/components/sync/sessions_impl/nudge_tracker.cc b/components/sync/engine_impl/cycle/nudge_tracker.cc
similarity index 99%
rename from components/sync/sessions_impl/nudge_tracker.cc
rename to components/sync/engine_impl/cycle/nudge_tracker.cc
index e2cf767281516e5945e9bf064282c2a8b07511a6..08df5e779efa29508a9af640b8f3727f8c1b198a 100644
--- a/components/sync/sessions_impl/nudge_tracker.cc
+++ b/components/sync/engine_impl/cycle/nudge_tracker.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/sync/sessions_impl/nudge_tracker.h"
+#include "components/sync/engine_impl/cycle/nudge_tracker.h"
 
 #include <stddef.h>
 
@@ -13,7 +13,6 @@
 #include "components/sync/protocol/sync.pb.h"
 
 namespace syncer {
-namespace sessions {
 
 namespace {
 
@@ -406,5 +405,4 @@ void NudgeTracker::SetDefaultNudgeDelay(base::TimeDelta nudge_delay) {
   minimum_local_nudge_delay_ = nudge_delay;
 }
 
-}  // namespace sessions
 }  // namespace syncer