Share Group plumbing in Blink; Remove WebGL from default share group

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index 40214beabcf07bb76d8bcb3a3070d9a825edfd95..e3e27f98e54c81a53e39fdbf721218dfcb31d3c7 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -552,7 +552,11 @@ public:
     //
     // May return null if GPU is not supported.
     // Returns newly allocated and initialized offscreen WebGraphicsContext3D instance.
+#ifdef ENABLE_EXPLICIT_GL_SHARE_GROUPS
+    virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&, WebGraphicsContext3D* share_context) { return 0; }
+#else
     virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&) { return 0; }

[Zhenyao Mo, 2014/03/03 18:39:49]

I think getting rid of the other signature (the one without share_context) is
better, but don't feel it's a big deal.

[bajones, 2014/03/03 18:48:27]

The idea is to get rid of it, but it can't be removed until everything is landed
and enabled. I'll be doing it in a follow-up patch.

+#endif
 
     // Returns a newly allocated and initialized offscreen context provider. The provider may return a null
     // graphics context if GPU is not supported.