Enable clang warning for ignored attributes.

content/public/browser/presentation_session_message.h

 // Copyright 2015 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_PUBLIC_BROWSER_PRESENTATION_SESSION_MESSAGE_H_
 #define CONTENT_PUBLIC_BROWSER_PRESENTATION_SESSION_MESSAGE_H_
 
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
-enum CONTENT_EXPORT PresentationMessageType {
+enum PresentationMessageType {
   TEXT,
   ARRAY_BUFFER,
   BLOB,
 };
 
 // Represents a presentation session message.
 // If this is a text message, |data| is null; otherwise, |message| is null.
 // Empty messages are allowed.
 struct CONTENT_EXPORT PresentationSessionMessage {
  public:
@@ skipping 30 matching lines @@
                              scoped_ptr<std::string> message);
   PresentationSessionMessage(const std::string& presentation_url,
                              const std::string& presentation_id,
                              PresentationMessageType type,
                              scoped_ptr<std::vector<uint8_t>> data);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_PRESENTATION_SESSION_H_