Add a NavigationThrottle to the public content/ interface

content/public/browser/navigation_throttle.cc

Index: content/public/browser/navigation_throttle.cc
diff --git a/content/public/browser/navigation_throttle.cc b/content/public/browser/navigation_throttle.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ac3b3aa405654418ac2e76e63b2380bc4ed16164
--- /dev/null
+++ b/content/public/browser/navigation_throttle.cc
@@ -0,0 +1,23 @@
+// 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_throttle.h"
+
+namespace content {
+
+NavigationThrottle::NavigationThrottle(NavigationHandle* navigation_handle)
+    : navigation_handle_(navigation_handle) {}
+
+NavigationThrottle::~NavigationThrottle() {}
+
+NavigationThrottle::ThrottleCheckResult NavigationThrottle::WillStartRequest() {
+  return NavigationThrottle::PROCEED;
+}
+
+NavigationThrottle::ThrottleCheckResult
+NavigationThrottle::WillRedirectRequest() {
+  return NavigationThrottle::PROCEED;
+}
+
+}  // namespace content