Remove InsecureContentInfobarDelegate, which has been broken for a while

chrome/browser/infobars/insecure_content_infobar_delegate.h

-// Copyright (c) 2011 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_INFOBARS_INSECURE_CONTENT_INFOBAR_DELEGATE_H_
-#define CHROME_BROWSER_INFOBARS_INSECURE_CONTENT_INFOBAR_DELEGATE_H_
-
-#include "base/macros.h"
-#include "components/infobars/core/confirm_infobar_delegate.h"
-
-class InfoBarService;
-
-// Base class for delegates that show warnings on HTTPS pages which try to
-// display or run insecure content.
-class InsecureContentInfoBarDelegate : public ConfirmInfoBarDelegate {
- public:
-  // Creates an insecure content infobar and delegate and adds the infobar to
-  // |infobar_service|, replacing any existing insecure content infobar.
-  static void Create(InfoBarService* infobar_service);
-
- private:
-  enum HistogramEvents {
-    DISPLAY_INFOBAR_SHOWN = 0,  // Infobar was displayed.
-    DISPLAY_USER_OVERRIDE,      // User clicked allow anyway button.
-    DISPLAY_USER_DID_NOT_LOAD,  // User clicked the don't load button.
-    DISPLAY_INFOBAR_DISMISSED,  // User clicked close button.
-    NUM_EVENTS
-  };
-
-  InsecureContentInfoBarDelegate();
-  ~InsecureContentInfoBarDelegate() override;
-
-  // ConfirmInfoBarDelegate:
-  infobars::InfoBarDelegate::InfoBarIdentifier GetIdentifier() const override;
-  void InfoBarDismissed() override;
-  InsecureContentInfoBarDelegate* AsInsecureContentInfoBarDelegate() override;
-  base::string16 GetMessageText() const override;
-  base::string16 GetButtonLabel(InfoBarButton button) const override;
-  bool Accept() override;
-  bool Cancel() override;
-  base::string16 GetLinkText() const override;
-  GURL GetLinkURL() const override;
-
-  DISALLOW_COPY_AND_ASSIGN(InsecureContentInfoBarDelegate);
-};
-
-#endif  // CHROME_BROWSER_INFOBARS_INSECURE_CONTENT_INFOBAR_DELEGATE_H_
-