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

components/sync/engine_impl/backoff_delay_provider.h

Index: components/sync/engine_impl/backoff_delay_provider.h
diff --git a/components/sync/engine_impl/backoff_delay_provider.h b/components/sync/engine_impl/backoff_delay_provider.h
index 454340b03f11962cc8cd9f08de3a68a395e7485e..09c664f74091f5d243da7d872f2d71933e4ed01a 100644
--- a/components/sync/engine_impl/backoff_delay_provider.h
+++ b/components/sync/engine_impl/backoff_delay_provider.h
@@ -10,9 +10,7 @@
 
 namespace syncer {
 
-namespace sessions {
 struct ModelNeutralState;
-}
 
 // A component used to get time delays associated with exponential backoff.
 class BackoffDelayProvider {
@@ -37,8 +35,7 @@ class BackoffDelayProvider {
 
   // Helper to calculate the initial value for exponential backoff.
   // See possible values and comments in polling_constants.h.
-  virtual base::TimeDelta GetInitialDelay(
-      const sessions::ModelNeutralState& state) const;
+  virtual base::TimeDelta GetInitialDelay(const ModelNeutralState& state) const;
 
  protected:
   BackoffDelayProvider(const base::TimeDelta& default_initial_backoff,