Revert of Fix crash when user closes window prior to the "Confirm Install" prompt showing

chrome/browser/ui/aura/native_window_tracker_aura.h

Index: chrome/browser/ui/aura/native_window_tracker_aura.h
diff --git a/chrome/browser/ui/aura/native_window_tracker_aura.h b/chrome/browser/ui/aura/native_window_tracker_aura.h
deleted file mode 100644
index cdd85ea4dae3f18fb78184aebc6b74a1061637e5..0000000000000000000000000000000000000000
--- a/chrome/browser/ui/aura/native_window_tracker_aura.h
+++ /dev/null
@@ -1,29 +0,0 @@
-// 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_UI_AURA_NATIVE_WINDOW_TRACKER_AURA_H_
-#define CHROME_BROWSER_UI_AURA_NATIVE_WINDOW_TRACKER_AURA_H_
-
-#include "chrome/browser/ui/native_window_tracker.h"
-#include "ui/aura/window_observer.h"
-
-class NativeWindowTrackerAura : public NativeWindowTracker,
-                                public aura::WindowObserver {
- public:
-  explicit NativeWindowTrackerAura(gfx::NativeWindow window);
-  ~NativeWindowTrackerAura() override;
-
-  // NativeWindowTracker:
-  bool WasNativeWindowClosed() const override;
-
- private:
-  // aura::WindowObserver:
-  void OnWindowDestroying(aura::Window* window) override;
-
-  aura::Window* window_;
-
-  DISALLOW_COPY_AND_ASSIGN(NativeWindowTrackerAura);
-};
-
-#endif  // CHROME_BROWSER_UI_AURA_NATIVE_WINDOW_TRACKER_AURA_H_