Don't apply the SandboxPlugins flag until we know a plugin will be used

third_party/WebKit/Source/core/html/HTMLPlugInElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 111 matching lines @@
     // HTMLElement function:
     bool hasCustomFocusLogic() const override;
     bool isPluginElement() const final;
 
     // Return any existing LayoutPart without triggering relayout, or 0 if it
     // doesn't yet exist.
     virtual LayoutPart* existingLayoutPart() const = 0;
     virtual void updateWidgetInternal() = 0;
 
     bool loadPlugin(const KURL&, const String& mimeType, const Vector<String>& paramNames, const Vector<String>& paramValues, bool useFallback, bool requireLayoutObject);
     bool pluginIsLoadable(const KURL&, const String& mimeType);

[pdr., 2016/02/02 04:32:42]

Can you add a short comment here that mentions the difference between
pluginIsLoadable and objectIsLoadable? I.e., they check different things and
both need to be checked for plugins.

[fs, 2016/02/22 18:36:56]

I renamed these two a bit in the latest PS, so hopefully the names are more
descriptive - I did add comments too though (belt _and_ suspenders).

+    bool objectIsLoadable(const KURL&, const String& mimeType);
     bool wouldLoadAsNetscapePlugin(const String& url, const String& serviceType);
 
     void setPersistedPluginWidget(Widget*);
 
     mutable RefPtr<SharedPersistent<v8::Object>> m_pluginWrapper;
     NPObject* m_NPObject;
     bool m_needsWidgetUpdate;
     bool m_shouldPreferPlugInsForImages;
 
     // Normally the Widget is stored in HTMLFrameOwnerElement::m_widget.
     // However, plugins can persist even when not rendered. In order to
     // prevent confusing code which may assume that widget() != null
     // means the frame is active, we save off m_widget here while
     // the plugin is persisting but not being displayed.
     RefPtrWillBeMember<Widget> m_persistedPluginWidget;
 };
 
 inline bool isHTMLPlugInElement(const HTMLElement& element)
 {
     return element.isPluginElement();
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLPlugInElement);
 
 } // namespace blink
 
 #endif // HTMLPlugInElement_h