10 files changed, 15 insertions, 0 deletions
diff --git a/sync/api/attachments/attachment.cc b/sync/api/attachments/attachment.cc
index 28e4e08..c9ef927 100644
--- a/sync/api/attachments/attachment.cc
+++ b/sync/api/attachments/attachment.cc
@@ -11,6 +11,8 @@
 
 namespace syncer {
 
+Attachment::Attachment(const Attachment& other) = default;
+
 Attachment::~Attachment() {}
 
 // Static.
diff --git a/sync/api/attachments/attachment.h b/sync/api/attachments/attachment.h
index 2f2bde0..711bc76 100644
--- a/sync/api/attachments/attachment.h
+++ b/sync/api/attachments/attachment.h
@@ -26,6 +26,7 @@ namespace syncer {
 // It is cheap to copy Attachments. Feel free to store and return by value.
 class SYNC_EXPORT Attachment {
  public:
+  Attachment(const Attachment& other);
   ~Attachment();
 
   // Default copy and assignment are welcome.
diff --git a/sync/api/attachments/attachment_id.cc b/sync/api/attachments/attachment_id.cc
index 7ebaeaf..6c8fb51 100644
--- a/sync/api/attachments/attachment_id.cc
+++ b/sync/api/attachments/attachment_id.cc
@@ -74,6 +74,8 @@ const sync_pb::AttachmentIdProto& AttachmentId::GetProto() const {
 AttachmentId::AttachmentId(sync_pb::AttachmentIdProto* proto)
     : proto_(proto) {}
 
+AttachmentId::AttachmentId(const AttachmentId& other) = default;
+
 size_t AttachmentId::GetSize() const {
   return proto_.Get().size_bytes();
 }
diff --git a/sync/api/attachments/attachment_id.h b/sync/api/attachments/attachment_id.h
index 3d2242c..b90bd4a 100644
--- a/sync/api/attachments/attachment_id.h
+++ b/sync/api/attachments/attachment_id.h
@@ -27,6 +27,7 @@ namespace syncer {
 // equivalent.
 class SYNC_EXPORT AttachmentId {
  public:
+  AttachmentId(const AttachmentId& other);
   ~AttachmentId();
 
   // Default copy and assignment are welcome.
diff --git a/sync/api/entity_change.cc b/sync/api/entity_change.cc
index 70f5add..ef0871e 100644
--- a/sync/api/entity_change.cc
+++ b/sync/api/entity_change.cc
@@ -28,6 +28,8 @@ EntityChange::EntityChange(std::string client_tag,
                            EntityDataPtr data)
     : client_tag_(client_tag), type_(type), data_(data) {}
 
+EntityChange::EntityChange(const EntityChange& other) = default;
+
 EntityChange::~EntityChange() {}
 
 }  // namespace syncer_v2
diff --git a/sync/api/entity_change.h b/sync/api/entity_change.h
index db1a9a0..60e512c 100644
--- a/sync/api/entity_change.h
+++ b/sync/api/entity_change.h
@@ -25,6 +25,7 @@ class SYNC_EXPORT EntityChange {
   static EntityChange CreateUpdate(std::string client_tag, EntityDataPtr data);
   static EntityChange CreateDelete(std::string client_tag);
 
+  EntityChange(const EntityChange& other);
   virtual ~EntityChange();
 
   std::string client_tag() const { return client_tag_; }
diff --git a/sync/api/sync_data.cc b/sync/api/sync_data.cc
index e40e7c3..8559b4c 100644
--- a/sync/api/sync_data.cc
+++ b/sync/api/sync_data.cc
@@ -77,6 +77,8 @@ SyncData::SyncData(int64_t id,
       attachment_service_(attachment_service),
       is_valid_(true) {}
 
+SyncData::SyncData(const SyncData& other) = default;
+
 SyncData::~SyncData() {}
 
 // Static.
diff --git a/sync/api/sync_data.h b/sync/api/sync_data.h
index a516eab..0463e32 100644
--- a/sync/api/sync_data.h
+++ b/sync/api/sync_data.h
@@ -39,6 +39,7 @@ class SYNC_EXPORT SyncData {
  public:
   // Creates an empty and invalid SyncData.
   SyncData();
+  SyncData(const SyncData& other);
   ~SyncData();
 
   // Default copy and assign welcome.
diff --git a/sync/api/sync_merge_result.cc b/sync/api/sync_merge_result.cc
index 0231acb0..f5607c7 100644
--- a/sync/api/sync_merge_result.cc
+++ b/sync/api/sync_merge_result.cc
@@ -18,6 +18,8 @@ SyncMergeResult::SyncMergeResult(ModelType type)
     pre_association_version_(0) {
 }
 
+SyncMergeResult::SyncMergeResult(const SyncMergeResult& other) = default;
+
 SyncMergeResult::~SyncMergeResult() {
 }
 
diff --git a/sync/api/sync_merge_result.h b/sync/api/sync_merge_result.h
index f164a4f..bcc2e5b 100644
--- a/sync/api/sync_merge_result.h
+++ b/sync/api/sync_merge_result.h
@@ -24,6 +24,7 @@ class SYNC_EXPORT SyncMergeResult {
  public:
   // Initialize an empty merge result for model type |type|.
   explicit SyncMergeResult(ModelType type);
+  SyncMergeResult(const SyncMergeResult& other);
   ~SyncMergeResult();
 
   // Default copy and assign welcome.