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

chrome/browser/chromeos/login/user_manager_impl.h

Index: chrome/browser/chromeos/login/user_manager_impl.h
diff --git a/chrome/browser/chromeos/login/user_manager_impl.h b/chrome/browser/chromeos/login/user_manager_impl.h
index 8bb42a1a8f2108b6430dd2ae6a1ede3a10243c3e..af888d595bc5483e825faa16d000e33155739c21 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.h
+++ b/chrome/browser/chromeos/login/user_manager_impl.h
@@ -47,7 +47,7 @@ class UserManagerImpl : public UserManager,
   virtual void DemoUserLoggedIn() OVERRIDE;
   virtual void GuestUserLoggedIn() OVERRIDE;
   virtual void EphemeralUserLoggedIn(const std::string& email) OVERRIDE;
-  virtual void SetLoggedInUserWallpaper() OVERRIDE;
+  virtual void InitializeWallpaper() OVERRIDE;
   virtual void UserSelected(const std::string& email) OVERRIDE;
   virtual void SessionStarted() OVERRIDE;
   virtual void RemoveUser(const std::string& email,