Quickly close tabs/window with long-running unload handlers.

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index 3e97d6eb5ebe79770cb5e99599408d0910bebd9a..f2146f574aa6772a39ef544900567f31ffc21d4d 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -371,6 +371,18 @@ class WebContents : public PageNavigator,
   // times, subsequent calls are ignored.
   virtual void OnCloseStarted() = 0;
 
+  // Notification that tab closing was cancelled. This can happen when a user
+  // cancels a window close via another tab's beforeunload dialog.
+  virtual void OnCloseCanceled() = 0;
+
+  // Set the time during close when unload is started. Normally, this is set
+  // after the beforeunload dialog. However, for a window close, it is set
+  // after all the beforeunload dialogs have finished.
+  virtual void OnUnloadStarted() = 0;
+
+  // Set the time during close when the tab is no longer visible.
+  virtual void OnUnloadDetachedStarted() = 0;
+
   // A render view-originated drag has ended. Informs the render view host and
   // WebContentsDelegate.
   virtual void SystemDragEnded() = 0;