app-shell: Introduce a ShellRendererMainDelegate.

apps/shell/app/shell_main_delegate.h

Index: apps/shell/app/shell_main_delegate.h
diff --git a/apps/shell/app/shell_main_delegate.h b/apps/shell/app/shell_main_delegate.h
index 45ba122f32378f7acb10febcbc8ed46c5a023c91..594f7634dabe0fdc5c354516623dd84843b05ef0 100644
--- a/apps/shell/app/shell_main_delegate.h
+++ b/apps/shell/app/shell_main_delegate.h
@@ -18,6 +18,7 @@ class ContentRendererClient;
 
 namespace apps {
 class ShellBrowserMainDelegate;
+class ShellRendererMainDelegate;
 
 class ShellMainDelegate : public content::ContentMainDelegate {
  public:
@@ -35,6 +36,10 @@ class ShellMainDelegate : public content::ContentMainDelegate {
   // The created object is owned by ShellBrowserMainParts.
   virtual ShellBrowserMainDelegate* CreateShellBrowserMainDelegate();
 
+  // The returned object is owned by ShellContentRendererClient.
+  virtual scoped_ptr<ShellRendererMainDelegate>
+      CreateShellRendererMainDelegate();
+
  private:
   // |process_type| is zygote, renderer, utility, etc. Returns true if the
   // process needs data from resources.pak.