Mouse event handlers use user gesture tokens on top-level LocalFrames.

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index 8d33eba40c5b70d75204e2d4f385d2877b167ecb..f6bcb12500e65639fa2e98ab21abb898379ef61f 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -1199,7 +1199,7 @@ bool EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
     RefPtr<FrameView> protector(m_frame->view());
 
     UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);
-    m_frame->tree().top()->eventHandler().m_lastMouseDownUserGestureToken = gestureIndicator.currentToken();
+    m_frame->localFrameRoot()->eventHandler().m_lastMouseDownUserGestureToken = gestureIndicator.currentToken();
 
     cancelFakeMouseMoveEvent();
     if (m_eventHandlerWillResetCapturingMouseEventsNode)
@@ -1515,7 +1515,7 @@ bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
 
     OwnPtr<UserGestureIndicator> gestureIndicator;
 
-    if (m_frame->tree().top()->eventHandler().m_lastMouseDownUserGestureToken)
+    if (m_frame->localFrameRoot()->eventHandler().m_lastMouseDownUserGestureToken)
         gestureIndicator = adoptPtr(new UserGestureIndicator(m_frame->tree().top()->eventHandler().m_lastMouseDownUserGestureToken.release()));
     else
         gestureIndicator = adoptPtr(new UserGestureIndicator(DefinitelyProcessingUserGesture));