Allow navigations to frames that aren't being unloaded in the unload handler.

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 905 matching lines @@
 
 FrameNavigationDisabler::FrameNavigationDisabler(LocalFrame& frame)
     : m_frame(&frame) {
   m_frame->disableNavigation();
 }
 
 FrameNavigationDisabler::~FrameNavigationDisabler() {
   m_frame->enableNavigation();
 }
 
+bool LocalFrame::isNavigationAllowed() const {
+  for (const Frame* currentFrame = this; currentFrame;
+       currentFrame = currentFrame->tree().parent()) {
+    if (currentFrame->isLocalFrame() &&

[dcheng, 2017/01/04 23:12:02]

I'd rather keep this non-recursive: I don't like having to downcast to local
frames, and it causes behavior differences between local and remote frames.

[lfg, 2017/01/09 19:04:12]

Done.

+        toLocalFrame(currentFrame)->m_navigationDisableCount > 0) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
 ScopedFrameBlamer::ScopedFrameBlamer(LocalFrame* frame) : m_frame(frame) {
   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