Add a NavigationThrottle to the public content/ interface

content/public/test/navigation_handle_tester.h

Index: content/public/test/navigation_handle_tester.h
diff --git a/content/public/test/navigation_handle_tester.h b/content/public/test/navigation_handle_tester.h
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+// 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_TEST_NAVIGATION_HANDLE_TESTER_H_
+#define CONTENT_PUBLIC_TEST_NAVIGATION_HANDLE_TESTER_H_
+
+#include "content/public/browser/navigation_throttle.h"
+#include "content/public/common/referrer.h"
+#include "ui/base/page_transition_types.h"
+#include "url/gurl.h"
+
+namespace content {
+class NavigationHandle;
+class NavigationThrottle;
+class WebContents;
+
+// This interface allows embedders of content/ to write tests that depend on a
+// test version of NavigationHandle, in particular unit tests that require
+// registering NavigationThrottles. In order to create a
+// NavigationHandleTester, use the static method provided.
+class NavigationHandleTester {
+ public:
+  // Returns the NavigationHandleTester for |handle|.
+  static NavigationHandleTester* For(NavigationHandle* handle);
+
+  // Creates a NavigationHandle enabled for testing.
+  static NavigationHandle* CreateTestNavigationHandle(
+      const GURL& url,
+      const GURL& validated_url,
+      bool is_main_frame,
+      WebContents* web_contents);
+
+  // Simulates the network request starting.
+  virtual NavigationThrottle::ThrottleCheckResult SimulateWillStartRequest(
+      bool is_post,
+      const Referrer& sanitized_referrer,
+      bool has_user_gesture,
+      ui::PageTransition transition,
+      bool is_external_protocol) = 0;
+
+  // Simulates the network request being redirected.
+  virtual NavigationThrottle::ThrottleCheckResult SimulateWillRedirectRequest(
+      const GURL& new_url,
+      const GURL& new_validated_url,
+      bool new_method_is_post,
+      const GURL& new_referrer_url,
+      bool new_is_external_protocol) = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_NAVIGATION_HANDLE_TESTER_H_