[sync] Componentize sync: Part 6: Add more SYNC_EXPORTs to files in src/sync/

sync/engine/backoff_delay_provider.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 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_ENGINE_BACKOFF_DELAY_PROVIDER_H_
 #define SYNC_ENGINE_BACKOFF_DELAY_PROVIDER_H_
 
 #include "base/time.h"
+#include "sync/base/sync_export.h"
 
 namespace syncer {
 
 namespace sessions {
 struct ModelNeutralState;
 }
 
 // A component used to get time delays associated with exponential backoff.
-class BackoffDelayProvider {
+class SYNC_EXPORT_PRIVATE BackoffDelayProvider {
  public:
   // Factory function to create a standard BackoffDelayProvider.
   static BackoffDelayProvider* FromDefaults();
 
   // Similar to above, but causes sync to retry very quickly (see
   // polling_constants.h) when it encounters an error before exponential
   // backoff.
   //
   // *** NOTE *** This should only be used if kSyncShortInitialRetryOverride
   // was passed to command line.
@@ skipping 18 matching lines @@
  private:
   const base::TimeDelta default_initial_backoff_;
   const base::TimeDelta short_initial_backoff_;
 
   DISALLOW_COPY_AND_ASSIGN(BackoffDelayProvider);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_BACKOFF_DELAY_PROVIDER_H_