Added extensions sync-related constants, switches, and clauses.

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index 282080588a5815f70e997dcd63eae18c70dec60f..04b98bf76b3a5f9d94332da8191b6a27311386f6 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -211,6 +211,7 @@ void ProfileSyncService::RegisterPreferences() {
   pref_service->RegisterBooleanPref(prefs::kSyncAutofill, enable_by_default);
   pref_service->RegisterBooleanPref(prefs::kSyncThemes, enable_by_default);
   pref_service->RegisterBooleanPref(prefs::kSyncTypedUrls, enable_by_default);
+  pref_service->RegisterBooleanPref(prefs::kSyncExtensions, enable_by_default);
 }
 
 void ProfileSyncService::ClearPreferences() {
@@ -392,6 +393,8 @@ const wchar_t* ProfileSyncService::GetPrefNameForDataType(
       return prefs::kSyncThemes;
     case syncable::TYPED_URLS:
       return prefs::kSyncTypedUrls;
+    case syncable::EXTENSIONS:
+      return prefs::kSyncExtensions;
     default:
       NOTREACHED();
       return NULL;