Remove Crostini preferences from incognito whitelist.

Preferences related to Crostini are removed from the persistent storage
list for incognito mode.
After this CL, if these preferences are changed from incognito mode,
they are only stored in memory and won't affect user profile.

Bug: 861722
Change-Id: I115c8fee12d105ebfe56a177d19d95d8e8106357
Reviewed-on: https://chromium-review.googlesource.com/1166825Reviewed-by: Timothy Loh <timloh@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581509}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -47,7 +47,6 @@
 
 #if defined(OS_CHROMEOS)
 #include "ash/public/cpp/ash_pref_names.h"
-#include "chrome/browser/chromeos/crostini/crostini_pref_names.h"
 #include "chromeos/chromeos_pref_names.h"
 #include "components/drive/drive_pref_names.h"
 #include "ui/base/ime/chromeos/extension_ime_util.h"
@@ -197,11 +196,6 @@ const char* temporary_incognito_whitelist[] = {
     ash::prefs::kTouchpadEnabled, ash::prefs::kTouchscreenEnabled,
 #endif  // defined(OS_CHROMEOS)
 
-// chrome/browser/chromeos/crostini/crostini_pref_names.h
-#if defined(OS_CHROMEOS)
-    crostini::prefs::kCrostiniEnabled,
-#endif  // defined(OS_CHROMEOS)
-
 // chrome/browser/accessibility/animation_policy_prefs.h
 #if !defined(OS_ANDROID)
     kAnimationPolicyAllowed, kAnimationPolicyOnce, kAnimationPolicyNone,