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

chrome/browser/sync/retry_verifier.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 CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_
 #define CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_
 #pragma once
 
 #include "base/time.h"
 
 namespace browser_sync {
+
 namespace sessions {
-struct SyncSessionSnapshot;
+class SyncSessionSnapshot;
 }  // namespace sessions
-}  // namespace browser_sync
 
-namespace browser_sync {
 // The minimum and maximum wait times for a retry. The actual retry would take
 // place somewhere in this range. The algorithm that calculates the retry wait
 // time uses rand functions.
 struct DelayInfo {
   int64 min_delay;
   int64 max_delay;
 };
 
 // Class to verify retries take place using the exponential backoff algorithm.
 class RetryVerifier {
@@ skipping 12 matching lines @@
   bool Succeeded() const { return done() && success_; }
 
  private:
   int retry_count_;
   base::Time last_sync_time_;
   DelayInfo delay_table_[kMaxRetry];
   bool success_;
   bool done_;
   DISALLOW_COPY_AND_ASSIGN(RetryVerifier);
 };
+
 }  // namespace browser_sync
+
 #endif  // CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_