[Sync] Renaming MetadataChanges to MetadataChangeList, slight metadata ownership tweak, and adding a few stub methods.

BUG=543405

Review URL: https://codereview.chromium.org/1478593002

Cr-Commit-Position: refs/heads/master@{#362450}

17 files changed, 196 insertions, 36 deletions

diff --git a/components/sync_driver/device_info_service.cc b/components/sync_driver/device_info_service.cc
index f210b2f..0a5949e 100644
--- a/components/sync_driver/device_info_service.cc
+++ b/components/sync_driver/device_info_service.cc
@@ -34,20 +34,20 @@ DeviceInfoService::DeviceInfoService(
 
 DeviceInfoService::~DeviceInfoService() {}
 
-syncer_v2::MetadataChanges* DeviceInfoService::CreateMetadataChanges() {
-  // TODO(skym): Implementation.
-  return nullptr;
+scoped_ptr<syncer_v2::MetadataChangeList>
+DeviceInfoService::CreateMetadataChangeList() {
+  return make_scoped_ptr(new syncer_v2::SimpleMetadataChangeList());
 }
 
 syncer::SyncError DeviceInfoService::MergeSyncData(
-    syncer_v2::MetadataChanges* metadata_changes,
+    scoped_ptr<syncer_v2::MetadataChangeList> metadata_change_list,
     syncer_v2::EntityDataList entity_data_list) {
   // TODO(skym): Implementation.
   return syncer::SyncError();
 }
 
 syncer::SyncError DeviceInfoService::ApplySyncChanges(
-    syncer_v2::MetadataChanges* metadata_changes,
+    scoped_ptr<syncer_v2::MetadataChangeList> metadata_change_list,
     syncer_v2::EntityChangeList entity_changes) {
   // TODO(skym): Implementation.
   return syncer::SyncError();
diff --git a/components/sync_driver/device_info_service.h b/components/sync_driver/device_info_service.h
index 76a4126..fdd1127 100644
--- a/components/sync_driver/device_info_service.h
+++ b/components/sync_driver/device_info_service.h
@@ -15,6 +15,7 @@
 #include "components/sync_driver/device_info_tracker.h"
 #include "components/sync_driver/local_device_info_provider.h"
 #include "sync/api/model_type_service.h"
+#include "sync/internal_api/public/simple_metadata_change_list.h"
 
 namespace syncer {
 class SyncError;
@@ -41,12 +42,12 @@ class DeviceInfoService : public syncer_v2::ModelTypeService,
   ~DeviceInfoService() override;
 
   // ModelTypeService implementation.
-  syncer_v2::MetadataChanges* CreateMetadataChanges() override;
+  scoped_ptr<syncer_v2::MetadataChangeList> CreateMetadataChangeList() override;
   syncer::SyncError MergeSyncData(
-      syncer_v2::MetadataChanges* metadata_changes,
+      scoped_ptr<syncer_v2::MetadataChangeList> metadata_change_list,
       syncer_v2::EntityDataList entity_data_list) override;
   syncer::SyncError ApplySyncChanges(
-      syncer_v2::MetadataChanges* metadata_changes,
+      scoped_ptr<syncer_v2::MetadataChangeList> metadata_change_list,
       syncer_v2::EntityChangeList entity_changes) override;
   void LoadMetadata(MetadataCallback callback) override;
   void GetData(ClientKeyList client_keys, DataCallback callback) override;
diff --git a/sync/BUILD.gn b/sync/BUILD.gn
index c6fd22b..d4d89d1 100644
--- a/sync/BUILD.gn
+++ b/sync/BUILD.gn
@@ -32,7 +32,7 @@ source_set("sync_core") {
     "api/entity_data.cc",
     "api/entity_data.h",
     "api/metadata_batch.h",
-    "api/metadata_changes.h",
+    "api/metadata_change_list.h",
     "api/model_type_change_processor.cc",
     "api/model_type_change_processor.h",
     "api/model_type_service.cc",
@@ -235,6 +235,8 @@ source_set("sync_core") {
     "internal_api/public/events/normal_get_updates_request_event.h",
     "internal_api/public/events/poll_get_updates_request_event.h",
     "internal_api/public/events/protocol_event.h",
+    "internal_api/public/fully_serialized_metadata_batch.cc",
+    "internal_api/public/fully_serialized_metadata_batch.h",
     "internal_api/public/http_bridge.h",
     "internal_api/public/http_bridge_network_resources.h",
     "internal_api/public/http_post_provider_factory.h",
@@ -264,6 +266,10 @@ source_set("sync_core") {
     "internal_api/public/sessions/update_counters.h",
     "internal_api/public/shared_model_type_processor.h",
     "internal_api/public/shutdown_reason.h",
+    "internal_api/public/simple_metadata_change_list.cc",
+    "internal_api/public/simple_metadata_change_list.h",
+    "internal_api/public/specifics_only_data_batch.cc",
+    "internal_api/public/specifics_only_data_batch.h",
     "internal_api/public/sync_auth_provider.h",
     "internal_api/public/sync_context.h",
     "internal_api/public/sync_context_proxy.h",
diff --git a/sync/api/data_batch.h b/sync/api/data_batch.h
index 63359cf..f66b5960 100644
--- a/sync/api/data_batch.h
+++ b/sync/api/data_batch.h
@@ -9,7 +9,7 @@
 
 namespace syncer_v2 {
 
-// Interface used by the processor and service to communicate about data.
+// Interface used by the processor to read data requested from the service.
 class SYNC_EXPORT DataBatch {
  public:
   DataBatch() {}
diff --git a/sync/api/metadata_batch.h b/sync/api/metadata_batch.h
index 56ffffb..459999c 100644
--- a/sync/api/metadata_batch.h
+++ b/sync/api/metadata_batch.h
@@ -9,7 +9,7 @@
 
 namespace syncer_v2 {
 
-// Interface used by the processor and service to communicate about metadata.
+// Interface used by the processor to read metadata requested from the service.
 class SYNC_EXPORT MetadataBatch {
  public:
   MetadataBatch() {}
diff --git a/sync/api/metadata_changes.h b/sync/api/metadata_change_list.h
index a3d4d3b..e4435a8 100644
--- a/sync/api/metadata_changes.h
+++ b/sync/api/metadata_change_list.h
@@ -2,20 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef SYNC_API_METADATA_CHANGES_H_
-#define SYNC_API_METADATA_CHANGES_H_
+#ifndef SYNC_API_METADATA_CHANGE_LIST_H_
+#define SYNC_API_METADATA_CHANGE_LIST_H_
 
 #include "sync/base/sync_export.h"
 
 namespace syncer_v2 {
 
 // Interface used by the processor and service to communicate about metadata.
-class SYNC_EXPORT MetadataChanges {
+class SYNC_EXPORT MetadataChangeList {
  public:
-  MetadataChanges() {}
-  virtual ~MetadataChanges() {}
+  MetadataChangeList() {}
+  virtual ~MetadataChangeList() {}
 };
 
 }  // namespace syncer_v2
 
-#endif  // SYNC_API_METADATA_CHANGES_H_
+#endif  // SYNC_API_METADATA_CHANGE_LIST_H_
diff --git a/sync/api/model_type_change_processor.h b/sync/api/model_type_change_processor.h
index 7781a0e..70874b3 100644
--- a/sync/api/model_type_change_processor.h
+++ b/sync/api/model_type_change_processor.h
@@ -17,7 +17,7 @@ class SyncError;
 
 namespace syncer_v2 {
 
-class MetadataChanges;
+class MetadataChangeList;
 
 // Interface used by the ModelTypeService to inform sync of local
 // changes.
@@ -30,11 +30,11 @@ class SYNC_EXPORT ModelTypeChangeProcessor {
   virtual void Put(const std::string& client_key,
                    const std::string& non_unique_name,
                    const sync_pb::EntitySpecifics& specifics,
-                   MetadataChanges* metadata_changes) = 0;
+                   MetadataChangeList* metadata_change_list) = 0;
 
   // Inform the processor of a deleted entity.
   virtual void Delete(const std::string& client_key,
-                      MetadataChanges* metadata_changes) = 0;
+                      MetadataChangeList* metadata_change_list) = 0;
 };
 
 }  // namespace syncer_v2
diff --git a/sync/api/model_type_service.h b/sync/api/model_type_service.h
index c09271b..aa798f5 100644
--- a/sync/api/model_type_service.h
+++ b/sync/api/model_type_service.h
@@ -23,7 +23,7 @@ namespace syncer_v2 {
 
 class DataBatch;
 class MetadataBatch;
-class MetadataChanges;
+class MetadataChangeList;
 
 // Interface implemented by model types to receive updates from sync via the
 // SharedModelTypeProcessor. Provides a way for sync to update the data and
@@ -42,16 +42,17 @@ class SYNC_EXPORT ModelTypeService {
 
   // Creates an object used to communicate changes in the sync metadata to the
   // model type store.
-  virtual MetadataChanges* CreateMetadataChanges() = 0;
+  virtual scoped_ptr<MetadataChangeList> CreateMetadataChangeList() = 0;
 
   // Perform the initial merge of data from the sync server. Should only need
   // to be called when sync is first turned on, not on every restart.
-  virtual syncer::SyncError MergeSyncData(MetadataChanges* metadata_changes,
-                                          EntityDataList entity_data_list) = 0;
+  virtual syncer::SyncError MergeSyncData(
+      scoped_ptr<MetadataChangeList> metadata_change_list,
+      EntityDataList entity_data_list) = 0;
 
   // Apply changes from the sync server locally.
   virtual syncer::SyncError ApplySyncChanges(
-      MetadataChanges* metadata_changes,
+      scoped_ptr<MetadataChangeList> metadata_change_list,
       EntityChangeList entity_changes) = 0;
 
   // Asynchronously retrieve the sync metadata.
diff --git a/sync/internal_api/public/fully_serialized_metadata_batch.cc b/sync/internal_api/public/fully_serialized_metadata_batch.cc
new file mode 100644
index 0000000..820bdeb
--- /dev/null
+++ b/sync/internal_api/public/fully_serialized_metadata_batch.cc
@@ -0,0 +1,20 @@
+// Copyright 2015 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 "sync/internal_api/public/fully_serialized_metadata_batch.h"
+
+namespace syncer_v2 {
+
+void FullySerializedMetadataBatch::PutMetadata(
+    const std::string& client_key,
+    const std::string& serialized_metadata) {
+  // TODO(skym): Implementation.
+}
+
+void FullySerializedMetadataBatch::PutGlobalMetadata(
+    const std::string& serialized_global_metadata) {
+  // TODO(skym): Implementation.
+}
+
+}  // namespace syncer_v2
diff --git a/sync/internal_api/public/fully_serialized_metadata_batch.h b/sync/internal_api/public/fully_serialized_metadata_batch.h
new file mode 100644
index 0000000..9982024
--- /dev/null
+++ b/sync/internal_api/public/fully_serialized_metadata_batch.h
@@ -0,0 +1,32 @@
+// Copyright 2015 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.
+
+#ifndef SYNC_INTERNAL_API_PUBLIC_FULLY_SERIALIZED_METADATA_BATCH_H_
+#define SYNC_INTERNAL_API_PUBLIC_FULLY_SERIALIZED_METADATA_BATCH_H_
+
+#include <string>
+
+#include "sync/api/metadata_batch.h"
+
+namespace syncer_v2 {
+
+// An implementation of MetadataBatch meant for services that have no need to
+// understand any of the sync metadata, and simply store/read it in a fully
+// serialized form.
+class FullySerializedMetadataBatch : public MetadataBatch {
+ public:
+  // Incorperates the given metadata at the given storage key into the batch,
+  // handling deserialization. Multiple invocations with the same client key is
+  // currently undefined.
+  void PutMetadata(const std::string& client_key,
+                   const std::string& serialized_metadata);
+
+  // Incorperates the given global metadata into the batch, handling
+  // deserialization. Multiple invocations will use the last value.
+  void PutGlobalMetadata(const std::string& serialized_global_metadata);
+};
+
+}  // namespace syncer_v2
+
+#endif  // SYNC_INTERNAL_API_PUBLIC_FULLY_SERIALIZED_METADATA_BATCH_H_
diff --git a/sync/internal_api/public/shared_model_type_processor.h b/sync/internal_api/public/shared_model_type_processor.h
index 0c47f69..a7d8f0f 100644
--- a/sync/internal_api/public/shared_model_type_processor.h
+++ b/sync/internal_api/public/shared_model_type_processor.h
@@ -69,9 +69,9 @@ class SYNC_EXPORT_PRIVATE SharedModelTypeProcessor
   void Put(const std::string& client_key,
            const std::string& non_unique_name,
            const sync_pb::EntitySpecifics& specifics,
-           MetadataChanges* metadata_changes) override;
+           MetadataChangeList* metadata_change_list) override;
   void Delete(const std::string& client_key,
-              MetadataChanges* metadata_changes) override;
+              MetadataChangeList* metadata_change_list) override;
 
   // Returns the list of pending updates.
   //
diff --git a/sync/internal_api/public/simple_metadata_change_list.cc b/sync/internal_api/public/simple_metadata_change_list.cc
new file mode 100644
index 0000000..27d2b41
--- /dev/null
+++ b/sync/internal_api/public/simple_metadata_change_list.cc
@@ -0,0 +1,19 @@
+// Copyright 2015 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 "sync/internal_api/public/simple_metadata_change_list.h"
+
+namespace syncer_v2 {
+
+SimpleMetadataChangeList::SimpleMetadataChangeList() {}
+
+SimpleMetadataChangeList::~SimpleMetadataChangeList() {}
+
+void SimpleMetadataChangeList::TranfserChanges(
+    ModelTypeStore* store,
+    ModelTypeStore::WriteBatch* write_batch) {
+  // TODO(skym): Implementation.
+}
+
+}  // namespace syncer_v2
diff --git a/sync/internal_api/public/simple_metadata_change_list.h b/sync/internal_api/public/simple_metadata_change_list.h
new file mode 100644
index 0000000..12bbe59
--- /dev/null
+++ b/sync/internal_api/public/simple_metadata_change_list.h
@@ -0,0 +1,31 @@
+// Copyright 2015 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.
+
+#ifndef SYNC_INTERNAL_API_PUBLIC_SIMPLE_METADATA_CHANGE_LIST_H_
+#define SYNC_INTERNAL_API_PUBLIC_SIMPLE_METADATA_CHANGE_LIST_H_
+
+#include "sync/api/metadata_change_list.h"
+#include "sync/api/model_type_store.h"
+#include "sync/base/sync_export.h"
+
+namespace syncer_v2 {
+
+// A MetadataChangeList implementation that is meant to be used in combination
+// with a ModelTypeStore. It accumulates changes in member fields, and then when
+// requested transfers them to the store/write batch.
+class SYNC_EXPORT SimpleMetadataChangeList : public MetadataChangeList {
+ public:
+  SimpleMetadataChangeList();
+  ~SimpleMetadataChangeList() override;
+
+  // Moves all currently accumulated changes into the write batch, clear out
+  // local copies. Calling this multiple times will work, but should not be
+  // necessary.
+  void TranfserChanges(ModelTypeStore* store,
+                       ModelTypeStore::WriteBatch* write_batch);
+};
+
+}  // namespace syncer_v2
+
+#endif  // SYNC_INTERNAL_API_PUBLIC_SIMPLE_METADATA_CHANGE_LIST_H_
diff --git a/sync/internal_api/public/specifics_only_data_batch.cc b/sync/internal_api/public/specifics_only_data_batch.cc
new file mode 100644
index 0000000..37896a7
--- /dev/null
+++ b/sync/internal_api/public/specifics_only_data_batch.cc
@@ -0,0 +1,15 @@
+// Copyright 2015 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 "sync/internal_api/public/specifics_only_data_batch.h"
+
+namespace syncer_v2 {
+
+void SpecificsOnlyDataBatch::Put(
+    const std::string& client_key,
+    scoped_ptr<sync_pb::EntitySpecifics> specifics) {
+  // TODO(skym): Implementation.
+}
+
+}  // namespace syncer_v2
diff --git a/sync/internal_api/public/specifics_only_data_batch.h b/sync/internal_api/public/specifics_only_data_batch.h
new file mode 100644
index 0000000..bb3aa19
--- /dev/null
+++ b/sync/internal_api/public/specifics_only_data_batch.h
@@ -0,0 +1,29 @@
+// Copyright 2015 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.
+
+#ifndef SYNC_INTERNAL_API_PUBLIC_SPECIFICS_ONLY_DATA_BATCH_H_
+#define SYNC_INTERNAL_API_PUBLIC_SPECIFICS_ONLY_DATA_BATCH_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "sync/api/data_batch.h"
+#include "sync/protocol/sync.pb.h"
+
+namespace syncer_v2 {
+
+// An implementation of DataBatch that only takes the simplest data from the
+// service. The processor may need to help populate some fields.
+class SpecificsOnlyDataBatch : public DataBatch {
+ public:
+  // Takes ownership of the specifics tied to a given key used for storage. Put
+  // should be called at most once for any given client_key. Multiple uses of
+  // the same client_key is currently undefined.
+  void Put(const std::string& client_key,
+           scoped_ptr<sync_pb::EntitySpecifics> specifics);
+};
+
+}  // namespace syncer_v2
+
+#endif  // SYNC_INTERNAL_API_PUBLIC_SPECIFICS_ONLY_DATA_BATCH_H_
diff --git a/sync/internal_api/shared_model_type_processor.cc b/sync/internal_api/shared_model_type_processor.cc
index 97275a9..e653d62 100644
--- a/sync/internal_api/shared_model_type_processor.cc
+++ b/sync/internal_api/shared_model_type_processor.cc
@@ -147,13 +147,12 @@ void SharedModelTypeProcessor::OnConnect(scoped_ptr<CommitQueue> worker) {
   FlushPendingCommitRequests();
 }
 
-void SharedModelTypeProcessor::Put(
-    const std::string& client_tag,
-    const std::string& non_unique_name,
-    const sync_pb::EntitySpecifics& specifics,
-    MetadataChanges* metadata_changes) {
+void SharedModelTypeProcessor::Put(const std::string& client_tag,
+                                   const std::string& non_unique_name,
+                                   const sync_pb::EntitySpecifics& specifics,
+                                   MetadataChangeList* metadata_change_list) {
   // TODO(skym): Update for new approach. Different objects, different caching,
-  // different loopups, metadat_changes, etc.
+  // different loopups, metadata_change_list, etc.
 
   DCHECK_EQ(type_, syncer::GetModelTypeFromSpecifics(specifics));
 
@@ -173,8 +172,9 @@ void SharedModelTypeProcessor::Put(
   FlushPendingCommitRequests();
 }
 
-void SharedModelTypeProcessor::Delete(const std::string& client_key,
-                                      MetadataChanges* metadata_changes) {
+void SharedModelTypeProcessor::Delete(
+    const std::string& client_key,
+    MetadataChangeList* metadata_change_list) {
   // TODO(skym): Update for new approach. Different caching, different lookup,
   // metadata changes.
 
diff --git a/sync/sync.gyp b/sync/sync.gyp
index bd41f74..45943fc 100644
--- a/sync/sync.gyp
+++ b/sync/sync.gyp
@@ -82,7 +82,7 @@
         'api/entity_data.cc',
         'api/entity_data.h',
         'api/metadata_batch.h',
-        'api/metadata_changes.h',
+        'api/metadata_change_list.h',
         'api/model_type_change_processor.cc',
         'api/model_type_change_processor.h',
         'api/model_type_service.cc',
@@ -288,6 +288,8 @@
         'internal_api/public/events/normal_get_updates_request_event.h',
         'internal_api/public/events/poll_get_updates_request_event.h',
         'internal_api/public/events/protocol_event.h',
+        'internal_api/public/fully_serialized_metadata_batch.h',
+        'internal_api/public/fully_serialized_metadata_batch.cc',
         'internal_api/public/http_bridge.h',
         'internal_api/public/http_bridge_network_resources.h',
         'internal_api/public/http_post_provider_factory.h',
@@ -317,6 +319,10 @@
         'internal_api/public/sessions/update_counters.h',
         'internal_api/public/shared_model_type_processor.h',
         'internal_api/public/shutdown_reason.h',
+        'internal_api/public/simple_metadata_change_list.cc',
+        'internal_api/public/simple_metadata_change_list.h',
+        'internal_api/public/specifics_only_data_batch.h',
+        'internal_api/public/specifics_only_data_batch.cc',
         'internal_api/public/sync_auth_provider.h',
         'internal_api/public/sync_context.h',
         'internal_api/public/sync_context_proxy.h',