Prevent the destruction of WebContents in NavigationThrottle methods

components/navigation_interception/intercept_navigation_throttle.h

Index: components/navigation_interception/intercept_navigation_throttle.h
diff --git a/components/navigation_interception/intercept_navigation_throttle.h b/components/navigation_interception/intercept_navigation_throttle.h
index 0b7f74605378266e5e09a549127d53639e1617a4..160e6450f01ee8569ea64de2955cbd1c8444ca81 100644
--- a/components/navigation_interception/intercept_navigation_throttle.h
+++ b/components/navigation_interception/intercept_navigation_throttle.h
@@ -24,7 +24,8 @@ 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 */)>
@@ -43,6 +44,8 @@ class InterceptNavigationThrottle : public content::NavigationThrottle {
 
   CheckCallback should_ignore_callback_;
 
+  base::WeakPtrFactory<InterceptNavigationThrottle> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(InterceptNavigationThrottle);
 };