[Chrome OS] Implement the device wallpaper policy.

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

 // Copyright 2014 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/chromeos/login/ui/webui_login_display.h"
 
 #include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
 #include "chrome/browser/chromeos/login/lock/screen_locker.h"
 #include "chrome/browser/chromeos/login/screens/chrome_user_selection_screen.h"
 #include "chrome/browser/chromeos/login/signin_screen_controller.h"
@@ skipping 209 matching lines @@
   DCHECK(delegate_);
   if (delegate_)
     delegate_->MigrateUserData(old_password);
 }
 
 void WebUILoginDisplay::LoadWallpaper(const AccountId& account_id) {
   WallpaperManager::Get()->SetUserWallpaperDelayed(account_id);
 }
 
 void WebUILoginDisplay::LoadSigninWallpaper() {
-  WallpaperManager::Get()->SetDefaultWallpaperDelayed(
-      user_manager::SignInAccountId());
+  if (!WallpaperManager::Get()->SetDeviceWallpaperIfApplicable(
+          user_manager::SignInAccountId())) {
+    WallpaperManager::Get()->SetDefaultWallpaperDelayed(
+        user_manager::SignInAccountId());
+  }
 }
 
 void WebUILoginDisplay::OnSigninScreenReady() {
   SignInScreenController::Get()->OnSigninScreenReady();
 
   if (delegate_)
     delegate_->OnSigninScreenReady();
 }
 
 void WebUILoginDisplay::OnGaiaScreenReady() {
@@ skipping 92 matching lines @@
 }
 
 bool WebUILoginDisplay::IsUserWhitelisted(const AccountId& account_id) {
   DCHECK(delegate_);
   if (delegate_)
     return delegate_->IsUserWhitelisted(account_id);
   return true;
 }
 
 }  // namespace chromeos