Use the WebTestProxy for layout tests in content_shell

content/public/renderer/content_renderer_client.cc

Index: content/public/renderer/content_renderer_client.cc
diff --git a/content/public/renderer/content_renderer_client.cc b/content/public/renderer/content_renderer_client.cc
index 502b6b81cfea3c1c964a8ec094cf671650d16818..30d0731b21fd867a66950a50d1bb785cfe458d2f 100644
--- a/content/public/renderer/content_renderer_client.cc
+++ b/content/public/renderer/content_renderer_client.cc
@@ -14,6 +14,12 @@ std::string ContentRendererClient::GetDefaultEncoding() {
   return std::string();
 }
 
+bool ContentRendererClient::OverrideCreateRenderViewImpl(
+      RenderViewImplParams* params,
+      RenderViewImpl** render_view_impl) {
+  return false;
+}
+
 bool ContentRendererClient::OverrideCreatePlugin(
     RenderView* render_view,
     WebKit::WebFrame* frame,