Introduce ChromeZoomLevelPref, make zoom level prefs independent of profile prefs.

chrome/browser/chromeos/login/ui/webui_login_view.cc

Index: chrome/browser/chromeos/login/ui/webui_login_view.cc
diff --git a/chrome/browser/chromeos/login/ui/webui_login_view.cc b/chrome/browser/chromeos/login/ui/webui_login_view.cc
index 6bd2ea7790b0097ea26a0344a7dff8febc3cbb1f..45ed048fa442da3305aa7cb4f54ff637f7d6c5fe 100644
--- a/chrome/browser/chromeos/login/ui/webui_login_view.cc
+++ b/chrome/browser/chromeos/login/ui/webui_login_view.cc
@@ -25,6 +25,7 @@
 #include "chrome/browser/sessions/session_tab_helper.h"
 #include "chrome/browser/ui/autofill/chrome_autofill_client.h"
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
+#include "chrome/browser/ui/zoom/zoom_controller.h"
 #include "chrome/common/render_messages.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/session_manager_client.h"
@@ -38,6 +39,7 @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
+#include "content/public/common/renderer_preferences.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
@@ -212,9 +214,10 @@ void WebUILoginView::Init() {
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       web_contents);
   WebContentsObserver::Observe(web_contents);
-  renderer_preferences_util::UpdateFromSystemSettings(
-      web_contents->GetMutableRendererPrefs(),
-      signin_profile);
+  content::RendererPreferences* prefs = web_contents->GetMutableRendererPrefs();
+  renderer_preferences_util::UpdateFromSystemSettings(prefs, signin_profile);
+  prefs->default_zoom_level =
+      ZoomController::FromWebContents(web_contents)->GetDefaultZoomLevel();
 }
 
 const char* WebUILoginView::GetClassName() const {