[Sync] Make SESSIONS an implicit type

chrome/browser/sync/sync_prefs_unittest.cc

Index: chrome/browser/sync/sync_prefs_unittest.cc
diff --git a/chrome/browser/sync/sync_prefs_unittest.cc b/chrome/browser/sync/sync_prefs_unittest.cc
index b38b187f15aa681a0d2e1600aeffe0fb448ac0e6..43a50d4b82abac2021e74bfda4ee6184b4ce2185 100644
--- a/chrome/browser/sync/sync_prefs_unittest.cc
+++ b/chrome/browser/sync/sync_prefs_unittest.cc
@@ -38,6 +38,8 @@ syncer::ModelTypeSet GetUserVisibleTypes() {
   user_visible_types.Remove(syncer::AUTOFILL_PROFILE);
   user_visible_types.Remove(syncer::EXTENSION_SETTINGS);
   user_visible_types.Remove(syncer::SEARCH_ENGINES);
+  user_visible_types.Remove(syncer::SESSIONS);
+  user_visible_types.Remove(syncer::HISTORY_DELETE_DIRECTIVES);
   return user_visible_types;
 }
 
@@ -116,13 +118,12 @@ TEST_F(SyncPrefsTest, PreferredTypesNotKeepEverythingSynced) {
     if (it.Get() == syncer::EXTENSIONS) {
       expected_preferred_types.Put(syncer::EXTENSION_SETTINGS);
     }
-    if (it.Get() == syncer::SESSIONS) {
+    if (it.Get() == syncer::TYPED_URLS) {
       expected_preferred_types.Put(syncer::HISTORY_DELETE_DIRECTIVES);
+      expected_preferred_types.Put(syncer::SESSIONS);
     }
-    // TODO(akalin): Remove this when history delete directives are
-    // registered by default.
-    if (it.Get() == syncer::HISTORY_DELETE_DIRECTIVES) {
-      expected_preferred_types.Clear();
+    if (it.Get() == syncer::TABS) {
+      expected_preferred_types.Put(syncer::SESSIONS);
     }
     sync_prefs.SetPreferredDataTypes(user_types, preferred_types);
     EXPECT_TRUE(expected_preferred_types.Equals(