Prevent the destruction of WebContents in NavigationThrottle methods

components/navigation_interception/intercept_navigation_throttle.cc

 // 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 "components/navigation_interception/intercept_navigation_throttle.h"
 
 #include "components/navigation_interception/navigation_params.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_handle.h"
 
 namespace navigation_interception {
 
+namespace {
+
+// Runs the |should_ignore_callback|. This may result in the destruction of
+// |throttle|, hence why it is not done inside the NavigationThrottle itself.
+content::NavigationThrottle::ThrottleCheckResult CheckCallbackAndMaybeDestroy(
+    const InterceptNavigationThrottle::CheckCallback& should_ignore_callback,
+    content::WebContents* web_contents,
+    const NavigationParams& navigation_params,
+    base::WeakPtr<InterceptNavigationThrottle> throttle) {
+  bool should_ignore_navigation =
+      should_ignore_callback.Run(web_contents, navigation_params);
+  if (!throttle)
+    return content::NavigationThrottle::DESTROYED;
+  return should_ignore_navigation
+             ? content::NavigationThrottle::CANCEL_AND_IGNORE
+             : content::NavigationThrottle::PROCEED;
+}
+
+}  // namespace
+
 InterceptNavigationThrottle::InterceptNavigationThrottle(
     content::NavigationHandle* navigation_handle,
     CheckCallback should_ignore_callback)
     : content::NavigationThrottle(navigation_handle),
-      should_ignore_callback_(should_ignore_callback) {}
+      should_ignore_callback_(should_ignore_callback),
+      weak_factory_(this) {}
 
 InterceptNavigationThrottle::~InterceptNavigationThrottle() {}
 
 content::NavigationThrottle::ThrottleCheckResult
 InterceptNavigationThrottle::WillStartRequest() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return CheckIfShouldIgnoreNavigation(false);
 }
 
 content::NavigationThrottle::ThrottleCheckResult
 InterceptNavigationThrottle::WillRedirectRequest() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return CheckIfShouldIgnoreNavigation(true);
 }
 
 content::NavigationThrottle::ThrottleCheckResult
 InterceptNavigationThrottle::CheckIfShouldIgnoreNavigation(bool is_redirect) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   NavigationParams navigation_params(
       navigation_handle()->GetURL(), navigation_handle()->GetReferrer(),
       navigation_handle()->HasUserGesture(), navigation_handle()->IsPost(),
       navigation_handle()->GetPageTransition(), is_redirect,
       navigation_handle()->IsExternalProtocol(), true);
-
-  bool should_ignore_navigation = should_ignore_callback_.Run(
-      navigation_handle()->GetWebContents(), navigation_params);
-  return should_ignore_navigation
-             ? content::NavigationThrottle::CANCEL_AND_IGNORE
-             : content::NavigationThrottle::PROCEED;
+  return CheckCallbackAndMaybeDestroy(
+      should_ignore_callback_, navigation_handle()->GetWebContents(),
+      navigation_params, weak_factory_.GetWeakPtr());
 }
 
 }  // namespace navigation_interception