Create NavigationHandles for interstitials if needed

content/browser/frame_host/navigation_handle_impl.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 CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 
 #include "content/public/browser/navigation_handle.h"
 
 #include <stddef.h>
@@ skipping 108 matching lines @@
       bool new_method_is_post,
       const GURL& new_referrer_url,
       bool new_is_external_protocol) override;
   NavigationThrottle::ThrottleCheckResult CallWillProcessResponseForTesting(
       RenderFrameHost* render_frame_host,
       const std::string& raw_response_header) override;
   void CallDidCommitNavigationForTesting(const GURL& url) override;
 
   NavigationData* GetNavigationData() override;
 
+  // The NavigatorDelegate to notify/query for various navigation events.
+  // Normally this is the WebContents, except if this NavigationHandle was
+  // created during a navigation to an interstitial page. In this case it will
+  // be the InterstitialPage itself.
+  //
+  // Note: due to the interstitial navigation case, all calls that can possibly
+  // expose the NavigationHandle to code outside of content/ MUST go though the
+  // NavigatorDelegate. In particular, the ContentBrowserClient should not be
+  // called directly form the NavigationHandle code. Thus, these calls will not
+  // expose the NavigationHandle when navigating to an InterstialPage.
   NavigatorDelegate* GetDelegate() const;
 
   RequestContextType GetRequestContextType() const;
 
   // Get the unique id from the NavigationEntry associated with this
   // NavigationHandle. Note that a synchronous, renderer-initiated navigation
   // will not have a NavigationEntry associated with it, and this will return 0.
   int pending_nav_entry_id() const { return pending_nav_entry_id_; }
 
   // Changes the pending NavigationEntry ID for this handle.  This is currently
@@ skipping 202 matching lines @@
   std::unique_ptr<NavigationData> navigation_data_;
 
   SSLStatus ssl_status_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_