Allow each WGC3D subclass to determine the correct GrGLInterface for its GrContext.

content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.cc

Index: content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.cc
===================================================================
--- content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.cc	(revision 98420)
+++ content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.cc	(working copy)
@@ -71,7 +71,6 @@
     WebKit::WebView* web_view,
     bool render_directly_to_web_view) {
   TRACE_EVENT0("gpu", "WebGfxCtx3DCmdBfrImpl::initialize");
-  webkit_glue::BindSkiaToCommandBufferGL();
   RenderThread* render_thread = RenderThread::current();
   if (!render_thread)
     return false;
@@ -1039,6 +1038,12 @@
   swapbuffers_complete_callback_ = cb;
 }
 
+#if WEBKIT_USING_SKIA
+GrGLInterface* WebGraphicsContext3DCommandBufferImpl::grGLInterface() {
+  return webkit_glue::GetCommandBufferSkiaGLBinding();
+}
+#endif
+
 namespace {
 
 WGC3Denum convertReason(RendererGLContext::ContextLostReason reason) {