PlzNavigate: add cancel navigation logic for uncommitted requests

content/browser/frame_host/navigation_before_commit_info.h

 // Copyright 2014 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_BEFORE_COMMIT_INFO_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_BEFORE_COMMIT_INFO_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/time/time.h"
+#include "content/common/content_export.h"
 #include "content/public/common/page_transition_types.h"
 #include "content/public/common/referrer.h"
 #include "url/gurl.h"
 
 namespace content {
 
 // PlzNavigate:
 // Holds the parameters determined during the load of a navigation request until
 // the response is received. Initialized on the IO thread, then passed to the UI
 // thread where it should be used to send a FrameMsg_CommitNavigation message to
 // the renderer.
 struct NavigationBeforeCommitInfo {
-  NavigationBeforeCommitInfo() {};
+  CONTENT_EXPORT NavigationBeforeCommitInfo();
 
   // The url that is actually being loaded.
   GURL navigation_url;
 
   // A unique blob url to be subsequently requested by the renderer as the main
   // resource for the frame, that will be used to find the associated stream of
   // data.
   GURL stream_url;
 
   // TODO(clamy): Maybe add the redirect chain if needed by the renderer.
 
   // The navigationStart time to expose to JS for this navigation.
   // TODO(clamy): Add the other values that matter to the Navigation Timing API.
   base::TimeTicks browser_navigation_start;
+
+  // The unique ID of this navigation request.
+  int64 navigation_request_id;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_BEFORE_COMMIT_INFO_H_