Similar as extension, DOM UI needs to be created in its own process....

chrome/browser/tab_contents/render_view_host_manager_unittest.cc

Index: chrome/browser/tab_contents/render_view_host_manager_unittest.cc
===================================================================
--- chrome/browser/tab_contents/render_view_host_manager_unittest.cc	(revision 70813)
+++ chrome/browser/tab_contents/render_view_host_manager_unittest.cc	(working copy)
@@ -253,8 +253,6 @@
   EXPECT_TRUE(host);
   EXPECT_TRUE(host == manager.current_host());
   EXPECT_FALSE(manager.pending_render_view_host());
-  EXPECT_TRUE(manager.pending_dom_ui());
-  EXPECT_FALSE(manager.dom_ui());
 
   // It's important that the site instance get set on the DOM UI page as soon
   // as the navigation starts, rather than lazily after it commits, so we don't
@@ -263,11 +261,13 @@
   EXPECT_TRUE(host->site_instance()->has_site());
   EXPECT_EQ(url, host->site_instance()->site());
 
+  // The DOM UI is committed immediately because the RenderViewHost has not been
+  // used yet. UpdateRendererStateForNavigate() took the short cut path.
+  EXPECT_FALSE(manager.pending_dom_ui());
+  EXPECT_TRUE(manager.dom_ui());
+
   // Commit.
   manager.DidNavigateMainFrame(host);
-
-  EXPECT_FALSE(manager.pending_dom_ui());
-  EXPECT_TRUE(manager.dom_ui());
 }
 
 // Tests that chrome: URLs that are not DOM UI pages do not get grouped into