Implement NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.

content/public/browser/navigation_handle.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_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_
 #define CONTENT_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 216 matching lines @@
   // yet. The connection info may change during the navigation (e.g. after
   // encountering a server redirect).
   virtual net::HttpResponseInfo::ConnectionInfo GetConnectionInfo() = 0;
 
   // Resumes a navigation that was previously deferred by a NavigationThrottle.
   // Note: this may lead to the deletion of the NavigationHandle and its
   // associated NavigationThrottles.
   virtual void Resume() = 0;
 
   // Cancels a navigation that was previously deferred by a NavigationThrottle.
-  // |result| should be equal to NavigationThrottle::CANCEL or
-  // NavigationThrottle::CANCEL_AND_IGNORE.
+  // |result| should be equal to either:
+  //  - NavigationThrottle::CANCEL,
+  //  - NavigationThrottle::CANCEL_AND_IGNORE, or
+  //  - NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.
   // Note: this may lead to the deletion of the NavigationHandle and its
   // associated NavigationThrottles.
   virtual void CancelDeferredNavigation(
       NavigationThrottle::ThrottleCheckResult result) = 0;
 
   // Returns the ID of the URLRequest associated with this navigation. Can only
   // be called from NavigationThrottle::WillProcessResponse and
   // WebContentsObserver::ReadyToCommitNavigation.
   // In the case of transfer navigations, this is the ID of the first request
   // made. The transferred request's ID will not be tracked by the
@@ skipping 47 matching lines @@
 
   // The NavigationData that the embedder returned from
   // ResourceDispatcherHostDelegate::GetNavigationData during commit. This will
   // be a clone of the NavigationData.
   virtual NavigationData* GetNavigationData() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_HANDLE_H_