Plumbing explicit share groups through context creation

content/renderer/renderer_webkitplatformsupport_impl.h

Index: content/renderer/renderer_webkitplatformsupport_impl.h
diff --git a/content/renderer/renderer_webkitplatformsupport_impl.h b/content/renderer/renderer_webkitplatformsupport_impl.h
index ca772948a8dd8ee19400e4ab6d1eb346e71fe7c8..955ed86138212978910868425ad80ec9d0329d7d 100644
--- a/content/renderer/renderer_webkitplatformsupport_impl.h
+++ b/content/renderer/renderer_webkitplatformsupport_impl.h
@@ -133,7 +133,12 @@ class CONTENT_EXPORT RendererWebKitPlatformSupportImpl
   virtual bool processMemorySizesInBytes(
       size_t* private_bytes, size_t* shared_bytes);
   virtual blink::WebGraphicsContext3D* createOffscreenGraphicsContext3D(
+#ifdef ENABLE_EXPLICIT_GL_SHARE_GROUPS
+      const blink::WebGraphicsContext3D::Attributes& attributes,
+      blink::WebGraphicsContext3D* share_context);
+#else
       const blink::WebGraphicsContext3D::Attributes& attributes);
+#endif
   virtual blink::WebGraphicsContext3DProvider*
       createSharedOffscreenGraphicsContext3DProvider();
   virtual blink::WebCompositorSupport* compositorSupport();