[Sync] Add sync_export.h (Step 1 for componentizing sync)

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_
 
 #include "base/time.h"
 
+// TODO(akalin): Move this to somewhere in sync/ and make
+// sync/engine/polling_constants.h private.
+
 namespace syncer {
 namespace sessions {
 class SyncSessionSnapshot;
 }  // namespace sessions
 }  // namespace syncer
 
 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
@@ skipping 24 matching lines @@
   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_