Add a NavigationThrottle to the public content/ interface

components/navigation_interception/intercept_navigation_throttle.h

+// 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 COMPONENTS_NAVIGATION_INTERCEPTION_INTERCEPT_NAVIGATION_THROTTLE_H_
+#define COMPONENTS_NAVIGATION_INTERCEPTION_INTERCEPT_NAVIGATION_THROTTLE_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/navigation_throttle.h"
+
+class GURL;
+
+namespace content {
+class NavigationHandle;
+class WebContents;
+}
+
+namespace navigation_interception {
+
+class NavigationParams;
+
+// This class allows the provider of the Callback to selectively ignore top
+// level navigations.

[Charlie Reis, 2015/09/16 00:09:24]

Let's mention this is a UI thread class.  Might want corresponding DCHECKs in
the .cc file, since these used to be IO thread objects.

[clamy, 2015/09/16 01:03:22]

Done.

+class InterceptNavigationThrottle : public content::NavigationThrottle {
+ public:
+  typedef base::Callback<bool(content::WebContents* /* source */,
+                              const NavigationParams& /* navigation_params */)>
+      CheckCallback;
+
+  InterceptNavigationThrottle(content::NavigationHandle* navigation_handle,
+                              CheckCallback should_ignore_callback);
+  ~InterceptNavigationThrottle() override;
+
+  // content::NavigationThrottle implementation:
+  ThrottleCheckResult WillStartRequest() override;
+  ThrottleCheckResult WillRedirectRequest() override;
+
+ private:
+  ThrottleCheckResult CheckIfShouldIgnoreNavigation(bool is_redirect);
+
+  CheckCallback should_ignore_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(InterceptNavigationThrottle);
+};
+
+}  // namespace navigation_interception
+
+#endif  // COMPONENTS_NAVIGATION_INTERCEPTION_INTERCEPT_NAVIGATION_THROTTLE_H_