Add trace event for detecting main frame in loading metrics.

third_party/WebKit/Source/web/WebLocalFrameImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 284 matching lines @@
   WebFrameWidgetBase* frameWidget() const override;
   void copyImageAt(const WebPoint&) override;
   void saveImageAt(const WebPoint&) override;
   void setEngagementLevel(mojom::EngagementLevel) override;
   void clearActiveFindMatch() override;
   void usageCountChromeLoadTimes(const WebString& metric) override;
   base::SingleThreadTaskRunner* timerTaskRunner() override;
   base::SingleThreadTaskRunner* loadingTaskRunner() override;
   base::SingleThreadTaskRunner* unthrottledTaskRunner() override;
   WebInputMethodControllerImpl* inputMethodController() const override;
+  void* frameIdForTracing() const override;
 
   void extractSmartClipData(WebRect rectInViewport,
                             WebString& clipText,
                             WebString& clipHtml) override;
 
   // WebFrameImplBase methods:
   void initializeCoreFrame(FrameHost*,
                            FrameOwner*,
                            const AtomicString& name,
                            const AtomicString& uniqueName) override;
@@ skipping 185 matching lines @@
 
 DEFINE_TYPE_CASTS(WebLocalFrameImpl,
                   WebFrame,
                   frame,
                   frame->isWebLocalFrame(),
                   frame.isWebLocalFrame());
 
 }  // namespace blink
 
 #endif