Remove Proxy Config preferences from incognito whitelist.

Preferences related to proxy config 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: I2670d44b59443f1c26844612842402511d246e63
Reviewed-on: https://chromium-review.googlesource.com/1172133Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583183}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -19,8 +19,6 @@
 #include "components/metrics/metrics_pref_names.h"
 #include "components/omnibox/browser/omnibox_pref_names.h"
 #include "components/onc/onc_pref_names.h"
-#include "components/proxy_config/proxy_config_pref_names.h"
-#include "components/proxy_config/proxy_prefs.h"
 #include "components/rappor/rappor_pref_names.h"
 #include "components/reading_list/core/reading_list_pref_names.h"
 #include "components/search_engines/search_engines_pref_names.h"
@@ -782,15 +780,6 @@ const char* const kTemporaryIncognitoWhitelist[] = {
     onc::prefs::kDeviceOpenNetworkConfiguration,
     onc::prefs::kOpenNetworkConfiguration,
 
-    // components/proxy_config/proxy_config_pref_names.h
-    // proxy_config::prefs::kProxy,
-    proxy_config::prefs::kUseSharedProxies,
-
-    // components/proxy_config/proxy_prefs.h
-    ProxyPrefs::kDirectProxyModeName, ProxyPrefs::kAutoDetectProxyModeName,
-    ProxyPrefs::kPacScriptProxyModeName, ProxyPrefs::kFixedServersProxyModeName,
-    ProxyPrefs::kSystemProxyModeName,
-
     // components/reading_list/core/reading_list_pref_names.h
     reading_list::prefs::kReadingListHasUnseenEntries,