Reland - Replace FakeServer's implementation with LoopbackServer invocations.

components/sync/engine_impl/loopback_server/persistent_unique_client_entity.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/loopback_server/persistent_unique_client_entity.h"
 
 #include "base/guid.h"
+#include "base/rand_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "components/sync/base/hash_util.h"
 #include "components/sync/engine_impl/loopback_server/persistent_permanent_entity.h"
 #include "components/sync/protocol/sync.pb.h"
 
 using std::string;
 
 namespace syncer {
 
 PersistentUniqueClientEntity::PersistentUniqueClientEntity(
     const string& id,
     ModelType model_type,
     int64_t version,
     const string& name,
     const string& client_defined_unique_tag,
     const sync_pb::EntitySpecifics& specifics,
     int64_t creation_time,
     int64_t last_modified_time)
     : LoopbackServerEntity(id, model_type, version, name),
       client_defined_unique_tag_(client_defined_unique_tag),
       creation_time_(creation_time),
       last_modified_time_(last_modified_time) {
   SetSpecifics(specifics);
 }
 
 PersistentUniqueClientEntity::~PersistentUniqueClientEntity() {}
 
 // static
-std::unique_ptr<LoopbackServerEntity> PersistentUniqueClientEntity::Create(
+std::unique_ptr<LoopbackServerEntity>
+PersistentUniqueClientEntity::CreateFromEntity(
     const sync_pb::SyncEntity& client_entity) {
-  CHECK(client_entity.has_client_defined_unique_tag())
-      << "A PersistentUniqueClientEntity must have a client-defined unique "
-         "tag.";
   ModelType model_type = GetModelTypeFromSpecifics(client_entity.specifics());
-  string id = EffectiveIdForClientTaggedEntity(client_entity);
+  CHECK_NE(client_entity.has_client_defined_unique_tag(),
+           syncer::CommitOnlyTypes().Has(model_type))
+      << "A UniqueClientEntity should have a client-defined unique tag iff it "
+         "is not a CommitOnly type.";
+  // Without model type specific logic for each CommitOnly type, we cannot infer
+  // a reasonable tag from the specifics. We need uniqueness for how the server
+  // holds onto all objects, so simply make a new tag from a random  number.
+  string effective_tag = client_entity.has_client_defined_unique_tag()
+                             ? client_entity.client_defined_unique_tag()
+                             : base::Uint64ToString(base::RandUint64());
+  string id = LoopbackServerEntity::CreateId(model_type, effective_tag);
   return std::unique_ptr<LoopbackServerEntity>(new PersistentUniqueClientEntity(
       id, model_type, client_entity.version(), client_entity.name(),
       client_entity.client_defined_unique_tag(), client_entity.specifics(),
       client_entity.ctime(), client_entity.mtime()));
 }
 
 // static
-std::string PersistentUniqueClientEntity::EffectiveIdForClientTaggedEntity(
-    const sync_pb::SyncEntity& entity) {
-  return LoopbackServerEntity::CreateId(
-      GetModelTypeFromSpecifics(entity.specifics()),
-      entity.client_defined_unique_tag());
+std::unique_ptr<LoopbackServerEntity>
+PersistentUniqueClientEntity::CreateFromEntitySpecifics(
+    const string& name,
+    const sync_pb::EntitySpecifics& entity_specifics) {
+  ModelType model_type = GetModelTypeFromSpecifics(entity_specifics);
+  string client_defined_unique_tag = GenerateSyncableHash(model_type, name);
+  string id =
+      LoopbackServerEntity::CreateId(model_type, client_defined_unique_tag);
+  return std::unique_ptr<LoopbackServerEntity>(new PersistentUniqueClientEntity(
+      id, model_type, 0, name, client_defined_unique_tag, entity_specifics,
+      1337, 1337));
 }
 
 bool PersistentUniqueClientEntity::RequiresParentId() const {
   return false;
 }
 
 string PersistentUniqueClientEntity::GetParentId() const {
   // The parent ID for this type of entity should always be its ModelType's
   // root node.
   return LoopbackServerEntity::GetTopLevelId(GetModelType());
 }
 
 sync_pb::LoopbackServerEntity_Type
 PersistentUniqueClientEntity::GetLoopbackServerEntityType() const {
   return sync_pb::LoopbackServerEntity_Type_UNIQUE;
 }
 
 void PersistentUniqueClientEntity::SerializeAsProto(
     sync_pb::SyncEntity* proto) const {
   LoopbackServerEntity::SerializeBaseProtoFields(proto);
 
   proto->set_client_defined_unique_tag(client_defined_unique_tag_);
   proto->set_ctime(creation_time_);
   proto->set_mtime(last_modified_time_);
 }
 
 }  // namespace syncer