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

sync/sessions/sync_session_context.cc

 // 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.
 
 #include "sync/sessions/sync_session_context.h"
 
 #include "sync/sessions/debug_info_getter.h"
-#include "sync/sessions/session_state.h"
 #include "sync/util/extensions_activity_monitor.h"
 
 namespace browser_sync {
 namespace sessions {
 
 const unsigned int kMaxMessagesToRecord = 10;
 const unsigned int kMaxMessageSizeToRecord = 5 * 1024;
 
 SyncSessionContext::SyncSessionContext(
     ServerConnectionManager* connection_manager,
@@ skipping 59 matching lines @@
   for (UnthrottleTimes::const_iterator it = unthrottle_times_.begin();
        it != unthrottle_times_.end();
        ++it) {
     types.Put(it->first);
   }
   return types;
 }
 
 }  // namespace sessions
 }  // namespace browser_sync