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

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

Index: third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
index b4fd3fe539ce39913ff720a61d538780bdbdfdfb..222a4e02ce27fb3d427ec684553fc1c35090b7b8 100644
--- a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
@@ -254,6 +254,14 @@
   }
 }
 
+static bool allowsBeforeUnloadListeners(LocalDOMWindow* window) {
+  DCHECK(window);
+  LocalFrame* frame = window->frame();
+  if (!frame)
+    return false;
+  return frame->isMainFrame();
+}
+
 unsigned LocalDOMWindow::pendingUnloadEventListeners() const {
   return windowsWithUnloadEventListeners().count(
       const_cast<LocalDOMWindow*>(this));
@@ -1425,9 +1433,16 @@
     addUnloadEventListener(this);
   } else if (eventType == EventTypeNames::beforeunload) {
     UseCounter::count(document(), UseCounter::DocumentBeforeUnloadRegistered);
-    addBeforeUnloadEventListener(this);
-    if (frame() && !frame()->isMainFrame())
+    if (allowsBeforeUnloadListeners(this)) {
+      // This is confusingly named. It doesn't actually add the listener. It
+      // just increments a count so that we know we have listeners registered
+      // for the purposes of determining if we can fast terminate the renderer
+      // process.
+      addBeforeUnloadEventListener(this);
+    } else {
+      // Subframes return false from allowsBeforeUnloadListeners.
       UseCounter::count(document(), UseCounter::SubFrameBeforeUnloadRegistered);
+    }
   }
 }
 
@@ -1445,7 +1460,8 @@
 
   if (eventType == EventTypeNames::unload) {
     removeUnloadEventListener(this);
-  } else if (eventType == EventTypeNames::beforeunload) {
+  } else if (eventType == EventTypeNames::beforeunload &&
+             allowsBeforeUnloadListeners(this)) {
     removeBeforeUnloadEventListener(this);
   }
 }