Switch to standard integer types in chrome/browser/, part 2 of 4.

chrome/browser/external_protocol/external_protocol_observer.h

 // Copyright 2014 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_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_
 #define CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_
 
+#include "base/macros.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 // ExternalProtocolObserver is responsible for handling messages from
 // WebContents relating to external protocols.
 class ExternalProtocolObserver
     : public content::WebContentsObserver,
       public content::WebContentsUserData<ExternalProtocolObserver> {
  public:
   ~ExternalProtocolObserver() override;
 
   // content::WebContentsObserver overrides.
   void DidGetUserGesture() override;
 
  private:
   explicit ExternalProtocolObserver(content::WebContents* web_contents);
   friend class content::WebContentsUserData<ExternalProtocolObserver>;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalProtocolObserver);
 };
 
 #endif  // CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_