Cleanup remaining class/struct fwd declarations

headless/lib/browser/headless_devtools_manager_delegate.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 HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_
 #define HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_
 
 #include "content/public/browser/devtools_manager_delegate.h"
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/memory/weak_ptr.h"
 #include "base/values.h"
 
 namespace headless {
 class HeadlessBrowserImpl;
 class HeadlessBrowserContext;
-class HeadlessWebContentsImpl;
 
 class HeadlessDevToolsManagerDelegate
     : public content::DevToolsManagerDelegate {
  public:
   explicit HeadlessDevToolsManagerDelegate(
       base::WeakPtr<HeadlessBrowserImpl> browser);
   ~HeadlessDevToolsManagerDelegate() override;
 
   // DevToolsManagerDelegate implementation:
   base::DictionaryValue* HandleCommand(content::DevToolsAgentHost* agent_host,
@@ skipping 16 matching lines @@
       HeadlessDevToolsManagerDelegate::*)(const base::DictionaryValue* params);
 
   std::map<std::string, CommandMemberFnPtr> command_map_;
 
   HeadlessBrowserContext* default_browser_context_;
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_