Keep track in the browser of which frames have onunload and onbeforeunload handlers.

chrome/browser/ui/unload_controller.cc

Index: chrome/browser/ui/unload_controller.cc
diff --git a/chrome/browser/ui/unload_controller.cc b/chrome/browser/ui/unload_controller.cc
index c838992ef6116f0cb6ab3a604c2539db2cbd0ee2..1ba4531be3beeca7bed63b3631c3da24a4bff953 100644
--- a/chrome/browser/ui/unload_controller.cc
+++ b/chrome/browser/ui/unload_controller.cc
@@ -327,8 +327,13 @@ void UnloadController::ProcessPendingTabs(bool skip_beforeunload) {
       // we would like devtools to call its own beforeunload handlers first,
       // and then call beforeunload handlers for |web_contents|.
       // See DevToolsWindow::InterceptPageBeforeUnload for details.
-      if (!DevToolsWindow::InterceptPageBeforeUnload(web_contents))
-        web_contents->DispatchBeforeUnload();
+      if (!DevToolsWindow::InterceptPageBeforeUnload(web_contents)) {
+        if (web_contents->NeedToFireBeforeUnload()) {
+          web_contents->DispatchBeforeUnload();
+        } else {
+          ClearUnloadState(web_contents, true);
+        }
+      }
     } else {
       ClearUnloadState(web_contents, true);
     }