Add a basic stub Polymer settings page at chrome://md-settings.

chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc

Index: chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
diff --git a/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc b/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
index 120d49b201c8023e392cb767a2b59c88e72820c8..779e6d23d31e5d6a74435d002dd8434e849b7d63 100644
--- a/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
+++ b/chrome/browser/ui/webui/chrome_web_ui_controller_factory.cc
@@ -36,6 +36,7 @@
 #include "chrome/browser/ui/webui/interstitials/interstitial_ui.h"
 #include "chrome/browser/ui/webui/invalidations_ui.h"
 #include "chrome/browser/ui/webui/local_state/local_state_ui.h"
+#include "chrome/browser/ui/webui/md_settings_ui.h"
 #include "chrome/browser/ui/webui/memory_internals/memory_internals_ui.h"
 #include "chrome/browser/ui/webui/net_internals/net_internals_ui.h"
 #include "chrome/browser/ui/webui/omnibox/omnibox_ui.h"
@@ -367,6 +368,11 @@ WebUIFactoryFunction GetWebUIFactoryFunction(WebUI* web_ui,
     return &NewWebUI<IdentityInternalsUI>;
   if (url.host() == chrome::kChromeUINewTabHost)
     return &NewWebUI<NewTabUI>;
+  if (url.host() == chrome::kChromeUIMdSettingsHost &&
+      ::switches::MdSettingsEnabled()) {
+    LOG(ERROR) << "url host is MD settings host";

[stevenjb, 2015/02/04 02:19:15]

VLOG (I know it's less convenient but we shouldn't check in ERROR for non
errors)

[michaelpg, 2015/02/04 02:35:29]

I would just remove this logging altogether.

[Oren Blasberg, 2015/02/04 18:31:51]

Done. Sorry guys I must've forgotten to do 'git cl upload' one more time before
mailing the CL since I'd already removed this locally.

+    return &NewWebUI<MdSettingsUI>;
+  }
   // Android does not support plugins for now.
   if (url.host() == chrome::kChromeUIPluginsHost)
     return &NewWebUI<PluginsUI>;
@@ -378,6 +384,7 @@ WebUIFactoryFunction GetWebUIFactoryFunction(WebUI* web_ui,
   if (url.host() == chrome::kChromeUISettingsFrameHost ||
       (url.host() == chrome::kChromeUISettingsHost &&
        ::switches::AboutInSettingsEnabled())) {
+    LOG(ERROR) << "url host is regular settings host";

[stevenjb, 2015/02/04 02:19:15]

And definitely not here :)

[Oren Blasberg, 2015/02/04 18:31:51]

Done.

     return &NewWebUI<options::OptionsUI>;
   }
   if (url.host() == chrome::kChromeUISuggestionsInternalsHost)