Remove unused instant_overlay_controller_mac.h/mm

chrome/browser/ui/cocoa/tab_contents/instant_overlay_controller_mac.h

-// Copyright 2012 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_COCOA_TAB_CONTENTS_INSTANT_OVERLAY_CONTROLLER_MAC_H_
-#define CHROME_BROWSER_UI_COCOA_TAB_CONTENTS_INSTANT_OVERLAY_CONTROLLER_MAC_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "chrome/browser/ui/search/instant_overlay_controller.h"
-
-class Browser;
-@class OverlayableContentsController;
-
-class InstantOverlayControllerMac : public InstantOverlayController {
- public:
-  InstantOverlayControllerMac(Browser* browser,
-                              OverlayableContentsController* overlay);
-  ~InstantOverlayControllerMac() override;
-
- private:
-  // Overridden from InstantOverlayController:
-  void OverlayStateChanged(const InstantOverlayModel& model) override;
-
-  OverlayableContentsController* const overlay_;
-
-  DISALLOW_COPY_AND_ASSIGN(InstantOverlayControllerMac);
-};
-
-#endif  // CHROME_BROWSER_UI_COCOA_TAB_CONTENTS_INSTANT_OVERLAY_CONTROLLER_MAC_H_