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

chrome/browser/tab_contents/render_view_host_manager.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/tab_contents/render_view_host_manager.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "chrome/browser/dom_ui/dom_ui.h"
 #include "chrome/browser/dom_ui/dom_ui_factory.h"
@@ skipping 280 matching lines @@
     const NavigationEntry* cur_entry,
     const NavigationEntry* new_entry) const {
   DCHECK(new_entry);
 
   if (!cur_entry) {
     // Always choose a new process when navigating to extension URLs. The
     // process grouping logic will combine all of a given extension's pages
     // into the same process.
     if (new_entry->url().SchemeIs(chrome::kExtensionScheme))
       return true;
+    // When a tab is created, it starts as TYPE_NORMAL. If the new entry is a
+    // DOM UI page, it needs to be grouped with other DOM UI pages. This matches
+    // the logic when transitioning between DOM UI and normal pages.
+//    Profile* profile = delegate_->GetControllerForRenderManager().profile();
+//    if (DOMUIFactory::UseDOMUIForURL(profile, new_entry->url()))
+//      return true;

[Charlie Reis, 2011/01/06 23:30:54]

These shouldn't be commented out.

     return false;
   }
 
   // We can't switch a RenderView between view source and non-view source mode
   // without screwing up the session history sometimes (when navigating between
   // "view-source:http://foo.com/" and "http://foo.com/", WebKit doesn't treat
   // it as a new navigation). So require a view switch.
   if (cur_entry->IsViewSourceMode() != new_entry->IsViewSourceMode())
     return true;
 
@@ skipping 402 matching lines @@
       Source<NavigationController>(&delegate_->GetControllerForRenderManager()),
       Details<RenderViewHostSwitchedDetails>(&details));
 
   // This will cause the old RenderViewHost to delete itself.
   old_render_view_host->Shutdown();
 
   // Let the task manager know that we've swapped RenderViewHosts, since it
   // might need to update its process groupings.
   delegate_->NotifySwappedFromRenderManager();
 }