Enable user change background image in settings page in Aura build.

chrome/browser/chromeos/login/user.cc

Index: chrome/browser/chromeos/login/user.cc
diff --git a/chrome/browser/chromeos/login/user.cc b/chrome/browser/chromeos/login/user.cc
index 073c999477374f9cbf67bac1f2db8f9ac7b62bcb..9947f10046f5ea653c98460aa6f01cbcb1521258 100644
--- a/chrome/browser/chromeos/login/user.cc
+++ b/chrome/browser/chromeos/login/user.cc
@@ -32,6 +32,7 @@ User::User(const std::string& email, bool is_guest)
     : email_(email),
       oauth_token_status_(OAUTH_TOKEN_STATUS_UNKNOWN),
       image_index_(kInvalidImageIndex),
+      wallpaper_index_(kDefaultWallpaperIndex),
       image_is_stub_(false),
       is_guest_(is_guest) {
   // The email address of a demo user is for internal purposes only,
@@ -44,6 +45,10 @@ User::User(const std::string& email, bool is_guest)
 
 User::~User() {}
 
+void User::SetWallpaper(int wallpaper_index) {
+  wallpaper_index_ = wallpaper_index;
+}
+
 void User::SetImage(const SkBitmap& image, int image_index) {
   image_ = image;
   image_index_ = image_index;