Add create WGC3DInProcessCommandBuffer for on-screen context

webkit/gpu/context_provider_in_process.cc

Index: webkit/gpu/context_provider_in_process.cc
diff --git a/webkit/gpu/context_provider_in_process.cc b/webkit/gpu/context_provider_in_process.cc
index 8fa3fa216500bebb103ac583732e20932cb5aaf5..a8855ab41a545795fae252807835bd44a212e6c7 100644
--- a/webkit/gpu/context_provider_in_process.cc
+++ b/webkit/gpu/context_provider_in_process.cc
@@ -59,8 +59,9 @@ bool ContextProviderInProcess::InitializeOnMainThread() {
   attributes.shareResources = true;
   attributes.noAutomaticFlushes = true;
 
+  using webkit::gpu::WebGraphicsContext3DInProcessCommandBufferImpl;
   context3d_.reset(
-      new webkit::gpu::WebGraphicsContext3DInProcessCommandBufferImpl(
+      WebGraphicsContext3DInProcessCommandBufferImpl::CreateOffscreenContext(
           attributes));
 
   return context3d_;