chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/management/chrome_management_api_delegate.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_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_
 #define CHROME_BROWSER_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_
 
 #include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "chrome/browser/extensions/extension_uninstall_dialog.h"
 #include "extensions/browser/api/management/management_api_delegate.h"
 
-namespace favicon_base {
-struct FaviconImageResult;
-}  // namespace favicon_base
-
 class ChromeManagementAPIDelegate : public extensions::ManagementAPIDelegate {
  public:
   ChromeManagementAPIDelegate();
   ~ChromeManagementAPIDelegate() override;
 
   // ManagementAPIDelegate.
   void LaunchAppFunctionDelegate(
       const extensions::Extension* extension,
       content::BrowserContext* context) const override;
   GURL GetFullLaunchURL(const extensions::Extension* extension) const override;
@@ skipping 42 matching lines @@
                      const std::string& extension_id,
                      extensions::LaunchType launch_type) const override;
   GURL GetIconURL(const extensions::Extension* extension,
                   int icon_size,
                   ExtensionIconSet::MatchType match,
                   bool grayscale,
                   bool* exists) const override;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_