Log to UMA why we would load a third-party frame

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 331 matching lines @@
             frame()->page()->scrollingCoordinator()) {
       scrollingCoordinator->scrollableAreaScrollbarLayerDidChange(
           frame()->view(), HorizontalScrollbar);
       scrollingCoordinator->scrollableAreaScrollbarLayerDidChange(
           frame()->view(), VerticalScrollbar);
       scrollingCoordinator->scrollableAreaScrollLayerDidChange(frame()->view());
     }
   }
 
   frame()->selection().updateSecureKeyboardEntryIfActive();
+
+  m_document->maybeRecordLoadReason(Created);
+
   return m_document;
 }
 
 EventQueue* LocalDOMWindow::getEventQueue() const {
   return m_eventQueue.get();
 }
 
 void LocalDOMWindow::enqueueWindowEvent(Event* event) {
   if (!m_eventQueue)
     return;
@@ skipping 1193 matching lines @@
 
 LocalFrame* LocalDOMWindow::frame() const {
   // If the LocalDOMWindow still has a frame reference, that frame must point
   // back to this LocalDOMWindow: otherwise, it's easy to get into a situation
   // where script execution leaks between different LocalDOMWindows.
   SECURITY_DCHECK(!m_frame || m_frame->domWindow() == this);
   return m_frame;
 }
 
 }  // namespace blink