chrome: Cleanup class/struct forward declarations

chrome/browser/ui/autofill/card_unmask_prompt_view_tester.h

 // Copyright 2015 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_UI_AUTOFILL_CARD_UNMASK_PROMPT_VIEW_TESTER_H_
 #define CHROME_BROWSER_UI_AUTOFILL_CARD_UNMASK_PROMPT_VIEW_TESTER_H_
 
 #include <memory>
 
-namespace content {
-class WebContents;
-}
-
 namespace autofill {
 
 class CardUnmaskPromptView;
 
 // Functionality that helps to test an AutofillCardUnmaskPromptView.
 class CardUnmaskPromptViewTester {
  public:
   // Gets a AutofillCardUnmaskPromptViewTester for |view|.
   static std::unique_ptr<CardUnmaskPromptViewTester> For(
       CardUnmaskPromptView* view);
 
   virtual ~CardUnmaskPromptViewTester() {}
 
   virtual void Close() = 0;
 };
 
 }  // namespace autofill
 
 #endif  // CHROME_BROWSER_UI_AUTOFILL_CARD_UNMASK_PROMPT_VIEW_TESTER_H_