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 ec6203bcccbd8cfff011c8899fdd56a8fbf5303e..7fa11729c11441fe281da7c43ea4f26de72240f0 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 nullptr;
     }
-
-    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 nullptr;
     }