[Sync] Convert SyncSessionSnapshot to a copy-able class.

sync/internal_api/js_sync_manager_observer.h

 // Copyright (c) 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 SYNC_INTERNAL_API_JS_SYNC_MANAGER_OBSERVER_H_
 #define SYNC_INTERNAL_API_JS_SYNC_MANAGER_OBSERVER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 15 matching lines @@
 // Routes SyncManager events to a JsEventHandler.
 class JsSyncManagerObserver : public sync_api::SyncManager::Observer {
  public:
   JsSyncManagerObserver();
   virtual ~JsSyncManagerObserver();
 
   void SetJsEventHandler(const WeakHandle<JsEventHandler>& event_handler);
 
   // sync_api::SyncManager::Observer implementation.
   virtual void OnSyncCycleCompleted(
-      const sessions::SyncSessionSnapshot* snapshot) OVERRIDE;
+      const sessions::SyncSessionSnapshot& snapshot) OVERRIDE;
   virtual void OnConnectionStatusChange(
       sync_api::ConnectionStatus status) OVERRIDE;
   virtual void OnUpdatedToken(const std::string& token) OVERRIDE;
   virtual void OnPassphraseRequired(
       sync_api::PassphraseRequiredReason reason,
       const sync_pb::EncryptedData& pending_keys) OVERRIDE;
   virtual void OnPassphraseAccepted() OVERRIDE;
   virtual void OnBootstrapTokenUpdated(
       const std::string& bootstrap_token) OVERRIDE;
   virtual void OnEncryptedTypesChanged(
@@ skipping 13 matching lines @@
                     const std::string& name, const JsEventDetails& details);
 
   WeakHandle<JsEventHandler> event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(JsSyncManagerObserver);
 };
 
 }  // namespace browser_sync
 
 #endif  // SYNC_INTERNAL_API_JS_SYNC_MANAGER_OBSERVER_H_