add missing CONTENT_EXPORT

content/common/gamepad_seqlock.h

 // Copyright (c) 2011 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 CONTENT_COMMON_GAMEPAD_SEQLOCK_H_
 #define CONTENT_COMMON_GAMEPAD_SEQLOCK_H_
 
 #include "base/atomicops.h"
 #include "base/threading/platform_thread.h"
+#include "content/common/content_export.h"
 
 namespace content {
 
 // This SeqLock handles only *one* writer and multiple readers. It may be
 // suitable for low-contention with relatively infrequent writes, and many
 // readers. See:
 //   http://en.wikipedia.org/wiki/Seqlock
 //   http://www.concurrencykit.org/doc/ck_sequence.html
 // This implementation is based on ck_sequence.h from http://concurrencykit.org.
 //
 // Currently, this is used in only one location. It may make sense to
 // generalize with a higher-level construct that owns both the lock and the
 // data buffer, if it is to be used more widely.
 //
 // You must be very careful not to operate on potentially inconsistent read
 // buffers. If the read must be retry'd, the data in the read buffer could
 // contain any random garbage. e.g., contained pointers might be
 // garbage, or indices could be out of range. Probably the only suitable thing
 // to do during the read loop is to make a copy of the data, and operate on it
 // only after the read was found to be consistent.
-class GamepadSeqLock {
+class CONTENT_EXPORT GamepadSeqLock {
  public:
   GamepadSeqLock();
   base::subtle::Atomic32 ReadBegin();
   bool ReadRetry(base::subtle::Atomic32 version);
   void WriteBegin();
   void WriteEnd();
 
  private:
   base::subtle::Atomic32 sequence_;
   DISALLOW_COPY_AND_ASSIGN(GamepadSeqLock);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GAMEPAD_SEQLOCK_H_