Move Google URL preferences to incognito persistent whitelist.

Google URL preferences are moved to the persistent storage list for the
incognito mode.
This CL does not change any behavior.

Bug: 861722
Change-Id: I72c4cb075551b81c1ceeb04eaadbeff7f53447b5
Reviewed-on: https://chromium-review.googlesource.com/1176805Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584150}

chrome/browser/prefs/pref_service_incognito_whitelist.cc

@@ -122,6 +122,9 @@ const char* const kPersistentPrefNames[] = {
     metrics::prefs::kUninstallMetricsUptimeSec, metrics::prefs::kUkmCellDataUse,
     metrics::prefs::kUmaCellDataUse, metrics::prefs::kUserCellDataUse,
 
+    // Google URL prefs don't store user data and just keep track of the URL.
+    prefs::kLastKnownGoogleURL, prefs::kLastPromptedGoogleURL,
+
     // Rappor preferences are not used in incognito mode, but they are written
     // in startup if they don't exist. So if the startup would be in incognito,
     // they need to be persisted.
@@ -693,9 +696,6 @@ const char* const kTemporaryIncognitoWhitelist[] = {
     // components/flags_ui/flags_ui_pref_names.h
     flags_ui::prefs::kEnabledLabsExperiments,
 
-    // components/google/core/browser/google_pref_names.h
-    prefs::kLastKnownGoogleURL, prefs::kLastPromptedGoogleURL,
-
     // components/invalidation/impl/invalidation_prefs.h
     invalidation::prefs::kInvalidatorClientId,
     invalidation::prefs::kInvalidatorInvalidationState,