Remove Spell Check preferences from incognito whitelist.

Preferences related to Spell Check 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: I09b64981a24f918cd62d82e487b265b4a0179a7b
Reviewed-on: https://chromium-review.googlesource.com/1159368
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580171}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -27,7 +27,6 @@
 #include "components/rappor/rappor_prefs.h"
 #include "components/reading_list/core/reading_list_pref_names.h"
 #include "components/search_engines/search_engines_pref_names.h"
-#include "components/spellcheck/browser/pref_names.h"
 #include "components/startup_metric_utils/browser/pref_names.h"
 #include "components/suggestions/suggestions_pref_names.h"
 #include "components/ukm/ukm_pref_names.h"
@@ -877,13 +876,6 @@ const char* temporary_incognito_whitelist[] = {
     prefs::kDefaultSearchProviderEnabled, prefs::kSearchProviderOverrides,
     prefs::kSearchProviderOverridesVersion, prefs::kCountryIDAtInstall,
 
-    // components/spellcheck/browser/pref_names.h
-    spellcheck::prefs::kSpellCheckEnable,
-    spellcheck::prefs::kSpellCheckDictionaries,
-    spellcheck::prefs::kSpellCheckForcedDictionaries,
-    spellcheck::prefs::kSpellCheckDictionary,
-    spellcheck::prefs::kSpellCheckUseSpellingService,
-
     // components/startup_metric_utils/browser/pref_names.h
     startup_metric_utils::prefs::kLastStartupTimestamp,
     startup_metric_utils::prefs::kLastStartupVersion,