[Sync] Add two more USS integration tests.

components/sync/engine_impl/worker_entity_tracker.cc

 // Copyright 2014 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.
 
 #include "components/sync/engine_impl/worker_entity_tracker.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "components/sync/base/model_type.h"
@@ skipping 107 matching lines @@
   ack->sequence_number = sequence_number_;
   ack->specifics_hash = pending_commit_specifics_hash_;
 
   // Because an in-progress commit blocks the sync thread, we can assume that
   // the item we just committed successfully is exactly the one we have now.
   // Nothing changed it while the commit was happening.  Since we're now in
   // sync with the server, we can clear the pending commit.
   ClearPendingCommit();
 }
 
-void WorkerEntityTracker::ReceiveUpdate(int64_t version) {
-  if (version <= highest_gu_response_version_)
+void WorkerEntityTracker::ReceiveUpdate(const UpdateResponseData& update) {
+  if (update.response_version <= highest_gu_response_version_)
     return;
 
-  highest_gu_response_version_ = version;
+  highest_gu_response_version_ = update.response_version;
+  id_ = update.entity->id;

[pavely, 2016/09/16 16:11:08]

Could you adjust comment for entities_ in model_type_worker.h to mention that
the map is keyed by client tag hash. This way it will be easier to verify that
adjusting id_ will not break mapping. Also we could make
WorkerEntityTracker::client_tag_hash_ const, this way attempt to modify it will
cause compiler error.

[maxbogue, 2016/09/16 17:39:43]

Done and done.

 
   // Got an applicable update newer than any pending updates.  It must be safe
   // to discard the old encrypted update, if there was one.
   ClearEncryptedUpdate();
 
   if (IsInConflict()) {
     // Incoming update clobbers the pending commit on the sync thread.
     // The model thread can re-request this commit later if it wants to.
     ClearPendingCommit();
   }
@@ skipping 48 matching lines @@
 bool WorkerEntityTracker::IsServerKnown() const {
   return base_version_ != kUncommittedVersion;
 }
 
 void WorkerEntityTracker::ClearPendingCommit() {
   pending_commit_.reset();
   pending_commit_specifics_hash_.clear();
 }
 
 }  // namespace syncer_v2