PerformanceMonitor: do not maintain a vector of frames in the monitor, single ExecutionContext memb…

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
@@ skipping 373 matching lines @@
     DCHECK_EQ(FrameLoadTypeReload, loadType);
     m_navigationScheduler->scheduleReload();
   }
 }
 
 void LocalFrame::detach(FrameDetachType type) {
   // Note that detach() can be re-entered, so it's not possible to
   // DCHECK(!m_isDetaching) here.
   m_isDetaching = true;
 
+  if (!tree().parent() || !tree().parent()->isLocalFrame())

[caseq, 2016/12/01 02:45:30]

Why not just check for isLocalRoot()?

+    m_performanceMonitor->shutdown();
+
   PluginScriptForbiddenScope forbidPluginDestructorScripting;
   m_loader.stopAllLoaders();
   // Don't allow any new child frames to load in this frame: attaching a new
   // child frame during or after detaching children results in an attached
   // frame on a detached DOM tree, which is bad.
   SubframeLoadingDisabler disabler(*document());
   m_loader.dispatchUnloadEvent();
   detachChildren();
 
   // All done if detaching the subframes brought about a detach of this frame
@@ skipping 522 matching lines @@
   if (m_frame && m_frame->client() && m_frame->client()->frameBlameContext())
     m_frame->client()->frameBlameContext()->Enter();
 }
 
 ScopedFrameBlamer::~ScopedFrameBlamer() {
   if (m_frame && m_frame->client() && m_frame->client()->frameBlameContext())
     m_frame->client()->frameBlameContext()->Leave();
 }
 
 }  // namespace blink