Use a #fefefe solid color wallpaper background before user login for GAIA login flow

chrome/browser/chromeos/login/user_manager_impl.cc

 // Copyright (c) 2012 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/user_manager_impl.h"
 
 #include <vector>
 
 #include "ash/shell.h"
 #include "ash/desktop_background/desktop_background_controller.h"
@@ skipping 954 matching lines @@
 }
 
 void UserManagerImpl::GetLoggedInUserWallpaperProperties(
     User::WallpaperType* type,
     int* index) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (!IsUserLoggedIn() || IsLoggedInAsStub()) {
     *type = current_user_wallpaper_type_ = User::DEFAULT;
     *index = current_user_wallpaper_index_ = ash::GetInvalidWallpaperIndex();
+    if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnableNewOobe)) {
+      bool show_users;
+      CrosSettings::Get()->GetBoolean(kAccountsPrefShowUserNamesOnSignIn,
+                                      &show_users);
+      if (!show_users)
+        *index = current_user_wallpaper_index_ = ash::GetSolidColorIndex();
+    }
     return;
   }
 
   GetUserWallpaperProperties(GetLoggedInUser().email(), type, index);
 }
 
 void UserManagerImpl::SaveLoggedInUserWallpaperProperties(
     User::WallpaperType type,
     int index) {
   SaveUserWallpaperProperties(GetLoggedInUser().email(), type, index);
@@ skipping 476 matching lines @@
     BrowserThread::PostTask(
         BrowserThread::FILE,
         FROM_HERE,
         base::Bind(&UserManagerImpl::DeleteUserImage,
                    base::Unretained(this),
                    image_path));
   }
 }
 
 }  // namespace chromeos