PlzNavigate: fix timing issue in app window creation

content/browser/frame_host/navigator_delegate.h

 // Copyright 2013 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_NAVIGATOR_DELEGATE_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_DELEGATE_H_
 
 #include "base/strings/string16.h"
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/navigation_controller.h"
@@ skipping 16 matching lines @@
 // related events.
 class CONTENT_EXPORT NavigatorDelegate {
  public:
   // Called when a navigation started. The same NavigationHandle will be
   // provided for events related to the same navigation.
   virtual void DidStartNavigation(NavigationHandle* navigation_handle) {}
 
   // Called when a navigation was redirected.
   virtual void DidRedirectNavigation(NavigationHandle* navigation_handle) {}
 
+  // Called when the navigation is about to be committed in a renderer.
+  virtual void ReadyToCommitNavigation(NavigationHandle* navigation_handle) {}
+
   // Called when a navigation committed.
   virtual void DidCommitNavigation(NavigationHandle* navigation_handle) {}
 
   // Called when a document load resulting from the navigation stopped. Note
   // that |navigation_handle| will be destroyed at the end of this call.
   virtual void DidFinishNavigation(NavigationHandle* navigation_handle) {}
 
   // TODO(clamy): all methods below that are related to navigation
   // events should go away in favor of the ones above.
 
@@ skipping 80 matching lines @@
   // throbber stopping.
   virtual void DidStopLoading() {}
 
   // The load progress was changed.
   virtual void DidChangeLoadProgress() {}
 };
 
 }  // namspace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_DELEGATE_H_