Use the WebTestProxy for layout tests in content_shell

content/public/renderer/content_renderer_client.h

Index: content/public/renderer/content_renderer_client.h
diff --git a/content/public/renderer/content_renderer_client.h b/content/public/renderer/content_renderer_client.h
index e91470ab45abbf30786f7370b051cb8afed72580..7cae37197f6a89413c4c774dd58f4384665c268b 100644
--- a/content/public/renderer/content_renderer_client.h
+++ b/content/public/renderer/content_renderer_client.h
@@ -52,6 +52,8 @@ class WebMediaPlayerImpl;
 namespace content {
 
 class RenderView;
+class RenderViewImpl;
+struct RenderViewImplParams;
 
 // Embedder API for participating in renderer logic.
 class CONTENT_EXPORT ContentRendererClient {
@@ -73,6 +75,12 @@ class CONTENT_EXPORT ContentRendererClient {
   // Returns the default text encoding.
   virtual std::string GetDefaultEncoding();
 
+  // Allows the embedder to override creating a RenderViewImpl. The only way an
+  // embedder can achieve this is by using the layout tests support library.
+  virtual bool OverrideCreateRenderViewImpl(
+      RenderViewImplParams* params,
+      RenderViewImpl** render_view_impl);
+
   // Allows the embedder to override creating a plugin. If it returns true, then
   // |plugin| will contain the created plugin, although it could be NULL. If it
   // returns false, the content layer will create the plugin.