components: Cleanup class/struct fwd declarations

components/visitedlink/browser/visitedlink_delegate.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 COMPONENTS_VISITEDLINK_BROWSER_VISITEDLINK_DELEGATE_H_
 #define COMPONENTS_VISITEDLINK_BROWSER_VISITEDLINK_DELEGATE_H_
 
 #include "base/memory/ref_counted.h"
 
 class GURL;
 
-namespace content {
-class BrowserContext;
-}
-
 namespace visitedlink {
 
 // Delegate class that clients of VisitedLinkMaster must implement.
 class VisitedLinkDelegate {
  public:
   // See RebuildTable.
   class URLEnumerator : public base::RefCountedThreadSafe<URLEnumerator> {
    public:
     // Call this with each URL to rebuild the table.
     virtual void OnURL(const GURL& url) = 0;
@@ skipping 16 matching lines @@
   // thread but the delegate is responsible for synchronizating the calls.
   virtual void RebuildTable(const scoped_refptr<URLEnumerator>& enumerator) = 0;
 
  protected:
   virtual ~VisitedLinkDelegate() {}
 };
 
 }  // namespace visitedlink
 
 #endif  // COMPONENTS_VISITEDLINK_BROWSER_VISITEDLINK_DELEGATE_H_