Add flag to use virtual contexts to WebGraphicsContext3D::Attributes

Source/Platform/chromium/public/WebGraphicsContext3D.h

 /*
  * Copyright (C) 2012 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 76 matching lines @@
             : alpha(true)
             , depth(true)
             , stencil(true)
             , antialias(true)
             , premultipliedAlpha(true)
             , canRecoverFromContextLoss(true)
             , noExtensions(false)
             , shareResources(true)
             , preferDiscreteGPU(false)
             , noAutomaticFlushes(false)
+            , useVirtualContext(false)
         {
         }
 
         bool alpha;
         bool depth;
         bool stencil;
         bool antialias;
         bool premultipliedAlpha;
         bool canRecoverFromContextLoss;
         bool noExtensions;
         bool shareResources;
         bool preferDiscreteGPU;
         bool noAutomaticFlushes;
+        bool useVirtualContext;
         // FIXME: ideally this would be a WebURL, but it is currently not
         // possible to pass a WebURL by value across the WebKit API boundary.
         // See https://bugs.webkit.org/show_bug.cgi?id=103793#c13 .
         WebString topDocumentURL;
     };
 
     class WebGraphicsContextLostCallback {
     public:
         virtual void onContextLost() = 0;
 
@@ skipping 361 matching lines @@
     virtual GrGLInterface* createGrGLInterface() { return onCreateGrGLInterface(); }
 
 protected:
     virtual GrGLInterface* onCreateGrGLInterface() { return 0; }
 
 };
 
 } // namespace WebKit
 
 #endif