Refactor preference syncing.

chrome/browser/prefs/browser_prefs.cc

Index: chrome/browser/prefs/browser_prefs.cc
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 08879d1ed6ef6b3da9a272b7b56890f9135fbec3..6d9dd691e70e889601eef294dc6f6a3616b0415e 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -176,7 +176,9 @@ void MigrateBrowserPrefs(PrefService* user_prefs, PrefService* local_state) {
 
   if ((current_version & WINDOWS_PREFS) == 0) {
     // Migrate the devtools split location preference.
-    local_state->RegisterIntegerPref(prefs::kDevToolsSplitLocation, -1);
+    local_state->RegisterIntegerPref(prefs::kDevToolsSplitLocation,
+                                     -1,
+                                     false /* don't sync pref */);
     DCHECK(user_prefs->FindPreference(prefs::kDevToolsSplitLocation));
     if (local_state->HasPrefPath(prefs::kDevToolsSplitLocation)) {
       user_prefs->SetInteger(prefs::kDevToolsSplitLocation,
@@ -185,7 +187,8 @@ void MigrateBrowserPrefs(PrefService* user_prefs, PrefService* local_state) {
     local_state->ClearPref(prefs::kDevToolsSplitLocation);
 
     // Migrate the browser window placement preference.
-    local_state->RegisterDictionaryPref(prefs::kBrowserWindowPlacement);
+    local_state->RegisterDictionaryPref(prefs::kBrowserWindowPlacement,
+                                        false /* don't sync pref */);
     DCHECK(user_prefs->FindPreference(prefs::kBrowserWindowPlacement));
     if (local_state->HasPrefPath(prefs::kBrowserWindowPlacement)) {
       const PrefService::Preference* pref =