Add a NavigationThrottle to the public content/ interface

content/browser/frame_host/navigation_handle_factory.h

Index: content/browser/frame_host/navigation_handle_factory.h
diff --git a/content/browser/frame_host/navigation_handle_factory.h b/content/browser/frame_host/navigation_handle_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..51b25b17e40141deb31172b89bac7ac19374f09e
--- /dev/null
+++ b/content/browser/frame_host/navigation_handle_factory.h
@@ -0,0 +1,35 @@
+// 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_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_FACTORY_H_
+#define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_FACTORY_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "url/gurl.h"
+
+namespace content {
+
+class NavigationHandleImpl;
+class NavigatorDelegate;
+
+class NavigationHandleFactory {
+ public:
+  static scoped_ptr<NavigationHandleImpl> Create(const GURL& url,
+                                                 const GURL& validated_url,
+                                                 bool is_main_frame,
+                                                 NavigatorDelegate* delegate);
+  static void SetFactoryForTesting(NavigationHandleFactory* factory);
+
+  virtual ~NavigationHandleFactory();
+
+  virtual scoped_ptr<NavigationHandleImpl> CreateHandle(
+      const GURL& url,
+      const GURL& validated_url,
+      bool is_main_frame,
+      NavigatorDelegate* delegate) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_FACTORY_H_