Fetch and actually set prefs (using chrome.send for now).

chrome/browser/ui/webui/md_settings_ui.cc

Index: chrome/browser/ui/webui/md_settings_ui.cc
diff --git a/chrome/browser/ui/webui/md_settings_ui.cc b/chrome/browser/ui/webui/md_settings_ui.cc
index 4c24d7f1a275d82fb57f36fbeabfc4585cb0bd25..2f7e40ac873a85e5d3e560a146e2c49377309931 100644
--- a/chrome/browser/ui/webui/md_settings_ui.cc
+++ b/chrome/browser/ui/webui/md_settings_ui.cc
@@ -7,6 +7,8 @@
 #include <string>
 
 #include "base/values.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/webui/options/core_options_handler.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/generated_resources.h"
 #include "content/public/browser/web_contents.h"
@@ -16,8 +18,24 @@
 #include "grit/settings_resources.h"
 #include "grit/settings_resources_map.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.h"
+#endif
+
 MdSettingsUI::MdSettingsUI(content::WebUI* web_ui)
     : content::WebUIController(web_ui) {
+  // TODO(jlklein): Remove handler logic once settingsPrivate is ready.
+#if defined(OS_CHROMEOS)
+  core_handler_ = new chromeos::options::CoreChromeOSOptionsHandler();
+#else
+  core_handler_ = new options::CoreOptionsHandler();
+#endif
+
+  core_handler_->set_handlers_host(this);
+  scoped_ptr<options::OptionsPageUIHandler> handler(core_handler_);
+  if (handler->IsEnabled())
+    web_ui->AddMessageHandler(handler.release());
+
   content::WebUIDataSource* html_source =
       content::WebUIDataSource::Create(chrome::kChromeUIMdSettingsHost);
 
@@ -36,3 +54,11 @@ MdSettingsUI::MdSettingsUI(content::WebUI* web_ui)
 
 MdSettingsUI::~MdSettingsUI() {
 }
+
+void MdSettingsUI::InitializeHandlers() {
+  Profile* profile = Profile::FromWebUI(web_ui());
+  DCHECK(!profile->IsOffTheRecord() || profile->IsGuestSession());

[Oren Blasberg, 2015/03/20 01:06:53]

should this be !profile->IsGuestSession() ?

[Jeremy Klein, 2015/03/20 01:11:05]

Nah guest sessions are ok for settings.

[michaelpg, 2015/03/20 02:34:28]

Yep. Incognito profiles are OK if you're in guest mode on Chrome OS, but on
desktop incognito opening settings should redirect you to a on-the-record
window. There were some changes around this recently.

+
+  core_handler_->InitializeHandler();
+  core_handler_->InitializePage();
+}