PlzNavigate: properly execute BeforeUnload on renderer initiated navigations

third_party/WebKit/public/web/WebLocalFrame.h

Index: third_party/WebKit/public/web/WebLocalFrame.h
diff --git a/third_party/WebKit/public/web/WebLocalFrame.h b/third_party/WebKit/public/web/WebLocalFrame.h
index 344c69251974ade929583061a32a4cc76a839aa9..aa939bd2b823939429c0fd745fe7953c85cde932 100644
--- a/third_party/WebKit/public/web/WebLocalFrame.h
+++ b/third_party/WebKit/public/web/WebLocalFrame.h
@@ -78,6 +78,11 @@ public:
 
     // Navigation ----------------------------------------------------------
 
+    // Runs beforeunload handlers for this frame and returns the value returned
+    // by handlers.
+    // Note: this may lead to the destruction of the frame.
+    virtual bool dispatchBeforeUnloadEvent(bool isReload) = 0;
+
     // Returns a WebURLRequest corresponding to the load of the WebHistoryItem.
     virtual WebURLRequest requestFromHistoryItem(const WebHistoryItem&, WebCachePolicy) const = 0;