Re-land: cc: Implement shared worker contexts.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 8997a58307d4207416a25d7e8cc9e1a9b69e6467..7cff9fe11725baf1e33deab37b21a4cf864af0bc 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1018,10 +1018,9 @@ scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
       // Cause the compositor to wait and try again.
       return scoped_ptr<cc::OutputSurface>();
     }
-
-    worker_context_provider = ContextProviderCommandBuffer::Create(
-        CreateGraphicsContext3D(false), RENDER_WORKER_CONTEXT);
-    if (!worker_context_provider.get()) {
+    worker_context_provider =
+        RenderThreadImpl::current()->SharedWorkerContextProvider();
+    if (!worker_context_provider) {
       // Cause the compositor to wait and try again.
       return scoped_ptr<cc::OutputSurface>();
     }