Enable Null Syncable ID which is different than Root ID.

sync/engine/directory_update_handler_unittest.cc

Index: sync/engine/directory_update_handler_unittest.cc
diff --git a/sync/engine/directory_update_handler_unittest.cc b/sync/engine/directory_update_handler_unittest.cc
index e7518ff6b9ff13673a071eda1269294b07e73a7a..8691a6a53709f60ef104d0a9375b42a0f70bcfc0 100644
--- a/sync/engine/directory_update_handler_unittest.cc
+++ b/sync/engine/directory_update_handler_unittest.cc
@@ -29,6 +29,7 @@
 
 namespace syncer {
 
+using syncable::Id;

[pavely, 2014/12/22 21:38:09]

nit: There are plenty of places in this file with syncable::Id. With your change
there are both: Id and syncable::Id. I think you should choose one and make sure
it is used consistently in the file.

[stanisc, 2014/12/22 22:44:19]

Done.

 using syncable::UNITTEST;
 
 static const int64 kDefaultVersion = 1000;
@@ -136,7 +137,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest, NewBookmarkTag) {
   sessions::StatusController status;
 
   // Add a bookmark item to the update message.
-  std::string root = syncable::GetNullId().GetServerId();
+  std::string root = Id::GetRoot().GetServerId();
   syncable::Id server_id = syncable::Id::CreateFromServerId("b1");
   scoped_ptr<sync_pb::SyncEntity> e =
       CreateUpdate(SyncableIdToProto(server_id), root, BOOKMARKS);
@@ -176,7 +177,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest,
 
   // Create an update that mimics the bookmark root.
   syncable::Id server_id = syncable::Id::CreateFromServerId("xyz");
-  std::string root = syncable::GetNullId().GetServerId();
+  std::string root = Id::GetRoot().GetServerId();
   scoped_ptr<sync_pb::SyncEntity> e =
       CreateUpdate(SyncableIdToProto(server_id), root, BOOKMARKS);
   e->set_server_defined_unique_tag("google_chrome_bookmarks");
@@ -209,7 +210,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest, ReceiveNonBookmarkItem) {
   sync_pb::GetUpdatesResponse gu_response;
   sessions::StatusController status;
 
-  std::string root = syncable::GetNullId().GetServerId();
+  std::string root = Id::GetRoot().GetServerId();
   syncable::Id server_id = syncable::Id::CreateFromServerId("xyz");
   scoped_ptr<sync_pb::SyncEntity> e =
       CreateUpdate(SyncableIdToProto(server_id), root, AUTOFILL);
@@ -272,8 +273,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest, GarbageCollectionByVersion) {
 
   scoped_ptr<sync_pb::SyncEntity> type_root =
       CreateUpdate(SyncableIdToProto(syncable::Id::CreateFromServerId("root")),
-                   syncable::GetNullId().GetServerId(),
-                   SYNCED_NOTIFICATIONS);
+                   Id::GetRoot().GetServerId(), SYNCED_NOTIFICATIONS);
   type_root->set_server_defined_unique_tag(
       ModelTypeToRootTag(SYNCED_NOTIFICATIONS));
   type_root->set_folder(true);
@@ -336,8 +336,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest, ContextVersion) {
 
   scoped_ptr<sync_pb::SyncEntity> type_root =
       CreateUpdate(SyncableIdToProto(syncable::Id::CreateFromServerId("root")),
-                   syncable::GetNullId().GetServerId(),
-                   SYNCED_NOTIFICATIONS);
+                   Id::GetRoot().GetServerId(), SYNCED_NOTIFICATIONS);
   type_root->set_server_defined_unique_tag(
       ModelTypeToRootTag(SYNCED_NOTIFICATIONS));
   type_root->set_folder(true);
@@ -417,8 +416,7 @@ TEST_F(DirectoryUpdateHandlerProcessUpdateTest,
 
   scoped_ptr<sync_pb::SyncEntity> type_root =
       CreateUpdate(SyncableIdToProto(syncable::Id::CreateFromServerId("root")),
-                   syncable::GetNullId().GetServerId(),
-                   ARTICLES);
+                   Id::GetRoot().GetServerId(), ARTICLES);
   type_root->set_server_defined_unique_tag(ModelTypeToRootTag(ARTICLES));
   type_root->set_folder(true);
 
@@ -575,7 +573,7 @@ sync_pb::EntitySpecifics DefaultBookmarkSpecifics() {
 TEST_F(DirectoryUpdateHandlerApplyUpdateTest, SimpleBookmark) {
   sessions::StatusController status;
 
-  std::string root_server_id = syncable::GetNullId().GetServerId();
+  std::string root_server_id = Id::GetRoot().GetServerId();
   int64 parent_handle =
       entry_factory()->CreateUnappliedNewBookmarkItemWithParent(
           "parent", DefaultBookmarkSpecifics(), root_server_id);
@@ -613,7 +611,7 @@ TEST_F(DirectoryUpdateHandlerApplyUpdateTest, SimpleBookmark) {
 TEST_F(DirectoryUpdateHandlerApplyUpdateTest,
        BookmarkChildrenBeforeParent) {
   // Start with some bookmarks whose parents are unknown.
-  std::string root_server_id = syncable::GetNullId().GetServerId();
+  std::string root_server_id = Id::GetRoot().GetServerId();
   int64 a_handle = entry_factory()->CreateUnappliedNewBookmarkItemWithParent(
       "a_child_created_first", DefaultBookmarkSpecifics(), "parent");
   int64 x_handle = entry_factory()->CreateUnappliedNewBookmarkItemWithParent(
@@ -903,7 +901,7 @@ TEST_F(DirectoryUpdateHandlerApplyUpdateTest,
 // fail due to hierarchy conflicts.  Others should succeed.
 TEST_F(DirectoryUpdateHandlerApplyUpdateTest, ItemsBothKnownAndUnknown) {
   // See what happens when there's a mixture of good and bad updates.
-  std::string root_server_id = syncable::GetNullId().GetServerId();
+  std::string root_server_id = Id::GetRoot().GetServerId();
   int64 u1_handle = entry_factory()->CreateUnappliedNewItemWithParent(
       "first_unknown_item", DefaultBookmarkSpecifics(), "unknown_parent");
   int64 k1_handle = entry_factory()->CreateUnappliedNewItemWithParent(
@@ -994,7 +992,7 @@ TEST_F(DirectoryUpdateHandlerApplyUpdateTest, UndecryptableData) {
   sync_pb::EntitySpecifics encrypted_bookmark;
   encrypted_bookmark.mutable_encrypted();
   AddDefaultFieldValue(BOOKMARKS, &encrypted_bookmark);
-  std::string root_server_id = syncable::GetNullId().GetServerId();
+  std::string root_server_id = Id::GetRoot().GetServerId();
   int64 folder_handle = entry_factory()->CreateUnappliedNewItemWithParent(
       "folder",
       encrypted_bookmark,