Revamp the MigrateBrowserPrefs and MigrateUserPrefs code.

chrome/common/pref_names.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 
 #include <stddef.h>
 
 #include "build/build_config.h"
 
 #include "components/autofill/core/common/autofill_pref_names.h"
 #include "components/bookmarks/common/bookmark_pref_names.h"
 #include "components/content_settings/core/common/pref_names.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_pref_names.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/password_manager/core/common/password_manager_pref_names.h"
 #include "components/signin/core/common/signin_pref_names.h"
 
+// TODO(rkaplow): Move obsolete prefs only needed in brwoser_prefs.cc to
+// browser_prefs.cc.
 namespace prefs {
 
 // Profile prefs. Please add Local State prefs below instead.
 extern const char kDefaultApps[];
 extern const char kDefaultAppsInstalled[];
 extern const char kDisableScreenshots[];
 extern const char kForceEphemeralProfiles[];
 extern const char kHomePageIsNewTabPage[];
 extern const char kHomePage[];
 extern const char kProfileIconVersion[];
@@ skipping 113 matching lines @@
 extern const char kSafeBrowsingIncidentsSent[];
 extern const char kIncognitoModeAvailability[];
 extern const char kSearchSuggestEnabled[];
 #if defined(OS_ANDROID)
 extern const char kContextualSearchEnabled[];
 #endif
 extern const char kConfirmToQuitEnabled[];
 extern const char kCookieBehavior[];  // OBSOLETE
 extern const char kPromptForDownload[];
 extern const char kAlternateErrorPagesEnabled[];
-extern const char kDnsStartupPrefetchList[];  // OBSOLETE
 extern const char kDnsPrefetchingStartupList[];
-extern const char kDnsHostReferralList[];  // OBSOLETE
 extern const char kDnsPrefetchingHostReferralList[];
 extern const char kDisableSpdy[];
 extern const char kHttpServerProperties[];
 extern const char kSpdyServers[];
 extern const char kAlternateProtocolServers[];
 extern const char kDisabledSchemes[];
 #if defined(OS_ANDROID) || defined(OS_IOS)
 extern const char kLastPolicyCheckTime[];
 #endif
 extern const char kInstantUIZeroSuggestUrlPrefix[];
-extern const char kMultipleProfilePrefMigration[];
 extern const char kNetworkPredictionEnabled[];
 extern const char kNetworkPredictionOptions[];
 extern const char kDefaultAppsInstallState[];
 extern const char kHideWebStoreIcon[];
 #if defined(OS_CHROMEOS)
 extern const char kTapToClickEnabled[];
 extern const char kTapDraggingEnabled[];
 extern const char kEnableTouchpadThreeFingerClick[];
 extern const char kNaturalScroll[];
 extern const char kPrimaryMouseButtonRight[];
@@ skipping 644 matching lines @@
 
 extern const char kRegisteredSupervisedUserWhitelists[];
 
 #if defined(ENABLE_EXTENSIONS)
 extern const char kAnimationPolicy[];
 #endif
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_