Add a NavigationThrottle to the public content/ interface

content/browser/frame_host/navigation_handle_factory.cc

Index: content/browser/frame_host/navigation_handle_factory.cc
diff --git a/content/browser/frame_host/navigation_handle_factory.cc b/content/browser/frame_host/navigation_handle_factory.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c2157b00bbb42d8a87febcd5ffebfd29f8da0631
--- /dev/null
+++ b/content/browser/frame_host/navigation_handle_factory.cc
@@ -0,0 +1,40 @@
+// 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/browser/frame_host/navigation_handle_factory.h"
+
+#include "base/logging.h"
+#include "content/browser/frame_host/navigation_handle_impl.h"
+
+namespace content {
+
+namespace {
+
+NavigationHandleFactory* g_factory = nullptr;
+
+}
+
+// static
+scoped_ptr<NavigationHandleImpl> NavigationHandleFactory::Create(
+    const GURL& url,
+    const GURL& validated_url,
+    bool is_main_frame,
+    NavigatorDelegate* delegate) {
+  if (g_factory)
+    return g_factory->CreateHandle(url, validated_url, is_main_frame, delegate);
+
+  return scoped_ptr<NavigationHandleImpl>(
+      new NavigationHandleImpl(url, validated_url, is_main_frame, delegate));
+}
+
+// static
+void NavigationHandleFactory::SetFactoryForTesting(
+    NavigationHandleFactory* factory) {
+  DCHECK(g_factory == nullptr || factory == nullptr);
+  g_factory = factory;
+}
+
+NavigationHandleFactory::~NavigationHandleFactory() {}
+
+}  // namespace content