Revert of Add a NavigationThrottle to the public content/ interface

content/public/browser/navigation_throttle.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 CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_
-#define CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_
-
-#include "content/common/content_export.h"
-
-namespace content {
-class NavigationHandle;
-
-// A NavigationThrottle tracks and allows interaction with a navigation on the
-// UI thread.
-class CONTENT_EXPORT NavigationThrottle {
- public:
-  // This is returned to the NavigationHandle to allow the navigation to
-  // proceed, or to cancel it.
-  enum ThrottleCheckResult {
-    PROCEED,
-    CANCEL_AND_IGNORE,
-  };
-
-  NavigationThrottle(NavigationHandle* navigation_handle);
-  virtual ~NavigationThrottle();
-
-  // Called when a network request is about to be made for this navigation.
-  virtual ThrottleCheckResult WillStartRequest();
-
-  // Called when a server redirect is received by the navigation.
-  virtual ThrottleCheckResult WillRedirectRequest();
-
-  // The NavigationHandle that is tracking the information related to this
-  // navigation.
-  NavigationHandle* navigation_handle() const { return navigation_handle_; }
-
- private:
-  NavigationHandle* navigation_handle_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_