Remove navigation_service_unittests, along with the service itself.

services/navigation/public/cpp/view_observer.h

-// Copyright 2016 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 SERVICES_NAVIGATION_PUBLIC_CPP_VIEW_OBSERVER_H_
-#define SERVICES_NAVIGATION_PUBLIC_CPP_VIEW_OBSERVER_H_
-
-namespace navigation {
-
-class View;
-
-class ViewObserver {
- public:
-  // Called when network activity for the application(s) within |view| starts or
-  // stops.
-  virtual void LoadingStateChanged(View* view) {}
-
-  // Called when the progress of network activity for the application(s) within
-  // |view| changes.
-  virtual void LoadProgressChanged(View* view, double progress) {}
-
-  // Called when a navigation occurs within |view|.
-  virtual void NavigationStateChanged(View* view) {}
-
-  // Called when the target URL of a mouse click at the current mouse position
-  // changes. Will provide an empty URL if no navigation would result from such
-  // a click.
-  virtual void HoverTargetURLChanged(View* view, const GURL& target_url) {}
-};
-
-}  // namespace navigation
-
-#endif  // SERVICES_NAVIGATION_PUBLIC_CPP_VIEW_OBSERVER_H_