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

sync/sessions/sync_session_context.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.
 
 // SyncSessionContext encapsulates the contextual information and engine
 // components specific to a SyncSession. A context is accessible via
 // a SyncSession so that session SyncerCommands and parts of the engine have
 // a convenient way to access other parts. In this way it can be thought of as
 // the surrounding environment for the SyncSession. The components of this
 // environment are either valid or not valid for the entire context lifetime,
 // or they are valid for explicitly scoped periods of time by using Scoped
 // installation utilities found below. This means that the context assumes no
 // ownership whatsoever of any object that was not created by the context
 // itself.
 //
 // It can only be used from the SyncerThread.
 
 #ifndef SYNC_SESSIONS_SYNC_SESSION_CONTEXT_H_
 #define SYNC_SESSIONS_SYNC_SESSION_CONTEXT_H_
 #pragma once
 
 #include <map>
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
 #include "sync/engine/model_safe_worker.h"
 #include "sync/engine/syncer_types.h"
+#include "sync/engine/sync_engine_event.h"
 #include "sync/engine/traffic_recorder.h"
 #include "sync/sessions/debug_info_getter.h"
 
 namespace syncable {
 class Directory;
 }
 
 namespace browser_sync {
 
 class ConflictResolver;
 class ExtensionsActivityMonitor;
 class ModelSafeWorkerRegistrar;
 class ServerConnectionManager;
 
 // Default number of items a client can commit in a single message.
 static const int kDefaultMaxCommitBatchSize = 25;
 
 namespace sessions {
 class ScopedSessionContextConflictResolver;
-struct SyncSessionSnapshot;
 class TestScopedSessionEventListener;
 
 class SyncSessionContext {
  public:
   SyncSessionContext(ServerConnectionManager* connection_manager,
                      syncable::Directory* directory,
                      ModelSafeWorkerRegistrar* model_safe_worker_registrar,
                      ExtensionsActivityMonitor* extensions_activity_monitor,
                      const std::vector<SyncEngineEventListener*>& listeners,
                      DebugInfoGetter* debug_info_getter,
@@ skipping 105 matching lines @@
   // The name of the account being synced.
   std::string account_name_;
 
   // The server limits the number of items a client can commit in one batch.
   int max_commit_batch_size_;
 
   // Some routing info history to help us clean up types that get disabled
   // by the user.
   ModelSafeRoutingInfo previous_session_routing_info_;
 
-  // Cache of last session snapshot information.
-  scoped_ptr<sessions::SyncSessionSnapshot> previous_session_snapshot_;
-
   // We use this to get debug info to send to the server for debugging
   // client behavior on server side.
   DebugInfoGetter* const debug_info_getter_;
 
   // This is a map from throttled data types to the time at which they can be
   // unthrottled.
   UnthrottleTimes unthrottle_times_;
 
   browser_sync::TrafficRecorder* traffic_recorder_;
 
@@ skipping 19 matching lines @@
  private:
   SyncSessionContext* context_;
   ConflictResolver* resolver_;
   DISALLOW_COPY_AND_ASSIGN(ScopedSessionContextConflictResolver);
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // SYNC_SESSIONS_SYNC_SESSION_CONTEXT_H_