Enable surprise me wallpaper for new profiles.

chrome/browser/chromeos/login/wallpaper_manager.cc

Index: chrome/browser/chromeos/login/wallpaper_manager.cc
diff --git a/chrome/browser/chromeos/login/wallpaper_manager.cc b/chrome/browser/chromeos/login/wallpaper_manager.cc
index 14cfbf3c22b0b5206cf5ea356b61a9500154d361..fc6b939e9ac30c7c1ae05aeaa8bc6d1cb08ddbb7 100644
--- a/chrome/browser/chromeos/login/wallpaper_manager.cc
+++ b/chrome/browser/chromeos/login/wallpaper_manager.cc
@@ -27,6 +27,8 @@
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
+#include "chrome/browser/chromeos/extensions/wallpaper_private_api.h"
+#include "chrome/browser/chromeos/login/login_display_host_impl.h"
 #include "chrome/browser/chromeos/login/startup_utils.h"
 #include "chrome/browser/chromeos/login/user.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
@@ -39,6 +41,7 @@
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
+#include "content/public/browser/web_ui.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/codec/jpeg_codec.h"
 #include "ui/gfx/image/image_skia_operations.h"
@@ -850,6 +853,14 @@ void WallpaperManager::RemoveObserver(WallpaperManager::Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
+void WallpaperManager::EnableSurpriseMe() {
+  static_cast<chromeos::LoginDisplayHostImpl*>(
+      chromeos::LoginDisplayHostImpl::default_host())

[Nikita (slow), 2014/02/28 10:44:14]

I assumes this call may happen inside session (when you sign in as a new user)
and LoginDisplayHost instance may have been already deleted.

+      ->GetOobeUI()
+      ->web_ui()
+      ->CallJavascriptFunction("SurpriseWallpaper.prototype.enableSurpriseMe");
+}
+
 void WallpaperManager::NotifyAnimationFinished() {
   FOR_EACH_OBSERVER(
       Observer, observers_, OnWallpaperAnimationFinished(last_selected_user_));