Prevent the destruction of WebContents in NavigationThrottle methods

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. This is a UI thread class.
-class InterceptNavigationThrottle : public content::NavigationThrottle {
+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_;
 
+  base::WeakPtrFactory<InterceptNavigationThrottle> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(InterceptNavigationThrottle);
 };
 
 }  // namespace navigation_interception
 
 #endif  // COMPONENTS_NAVIGATION_INTERCEPTION_INTERCEPT_NAVIGATION_THROTTLE_H_