Remove Settings Reset Prompt preferences from incognito whitelist.

Settings Reset Prompt preferences 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: I84164f5734290d20c2a50ed93139645b91561296
Reviewed-on: https://chromium-review.googlesource.com/1176808
Commit-Queue: Robert Shield <robertshield@chromium.org>
Reviewed-by: Robert Shield <robertshield@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583676}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -684,11 +684,6 @@ const char* const kTemporaryIncognitoWhitelist[] = {
 #endif  // defined(GOOGLE_CHROME_BUILD)
 #endif  // defined(OS_WIN)
 
-    prefs::kSettingsResetPromptPromptWave,
-    prefs::kSettingsResetPromptLastTriggeredForDefaultSearch,
-    prefs::kSettingsResetPromptLastTriggeredForStartupUrls,
-    prefs::kSettingsResetPromptLastTriggeredForHomepage,
-
 #if defined(OS_ANDROID)
     prefs::kClipboardLastModifiedTime,
 #endif