chrome: Cleanup class/struct forward declarations

chrome/browser/permissions/delegation_tracker.h

 // Copyright 2016 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_PERMISSIONS_DELEGATION_TRACKER_H_
 #define CHROME_BROWSER_PERMISSIONS_DELEGATION_TRACKER_H_
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
 
 #include "base/macros.h"
 
 namespace content {
 
 class RenderFrameHost;
-class WebContents;
 enum class PermissionType;
 
 }  // namespace content
 
 // Keeps track of which permissions are delegated to frames. There are two
 // operations possible:
 // 1) Setting the permissions which are delegated to a frame by its parent, and
 // 2) Querying whether a particular permission is granted to a frame.
 //
 // If a frame is destroyed or navigated, permissions will no longer be delegated
@@ skipping 23 matching lines @@
   void RenderFrameHostChanged(content::RenderFrameHost* rfh);
 
   std::unordered_map<content::RenderFrameHost*,
                      std::unique_ptr<DelegatedForChild>>
       delegated_permissions_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegationTracker);
 };
 
 #endif  // CHROME_BROWSER_PERMISSIONS_DELEGATION_TRACKER_H_