Revert of Add a NavigationThrottle to the public content/ interface

content/public/browser/navigation_handle.cc

-// 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.
-
-#include "content/public/browser/navigation_handle.h"
-
-#include "content/browser/frame_host/navigation_handle_impl.h"
-#include "content/browser/frame_host/navigator.h"
-#include "content/browser/web_contents/web_contents_impl.h"
-
-namespace content {
-
-WebContents* NavigationHandle::GetWebContents() {
-  // The NavigationHandleImpl cannot access the WebContentsImpl as it would be
-  // a layering violation, hence the cast here.
-  return static_cast<WebContentsImpl*>(
-      static_cast<NavigationHandleImpl*>(this)->delegate());
-}
-
-// static
-scoped_ptr<NavigationHandle> NavigationHandle::CreateNavigationHandleForTesting(
-    const GURL& url,
-    bool is_main_frame,
-    WebContents* web_contents) {
-  scoped_ptr<NavigationHandleImpl> handle_impl = NavigationHandleImpl::Create(
-      url, is_main_frame, static_cast<WebContentsImpl*>(web_contents));
-  return scoped_ptr<NavigationHandle>(handle_impl.Pass());
-}
-
-}  // namespace content