[Sync] Move snapshot cache from SBHI to PSS.

components/sync/engine/sync_engine.h

 // Copyright 2012 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.
 
 #ifndef COMPONENTS_SYNC_ENGINE_SYNC_ENGINE_H_
 #define COMPONENTS_SYNC_ENGINE_SYNC_ENGINE_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 121 matching lines @@
   virtual void Shutdown(ShutdownReason reason) = 0;
 
   // Turns on encryption of all present and future sync data.
   virtual void EnableEncryptEverything() = 0;
 
   // Obtain a handle to the UserShare needed for creating transactions. Should
   // not be called before we signal initialization is complete with
   // OnBackendInitialized().
   virtual UserShare* GetUserShare() const = 0;
 
-  // Called from any thread to obtain current status information in detailed or
-  // summarized form.
+  // Called from any thread to obtain current detailed status information.
   virtual Status GetDetailedStatus() = 0;
-  virtual SyncCycleSnapshot GetLastCycleSnapshot() const = 0;
 
   // Determines if the underlying sync engine has made any local changes to
   // items that have not yet been synced with the server.
   // ONLY CALL THIS IF OnInitializationComplete was called!
   virtual bool HasUnsyncedItems() const = 0;
 
   // Whether or not we are syncing encryption keys.
   virtual bool IsNigoriEnabled() const = 0;
 
   // Returns the type of passphrase being used to encrypt data. See
@@ skipping 42 matching lines @@
   // See SyncManager::OnCookieJarChanged.
   virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncEngine);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_ENGINE_SYNC_ENGINE_H_