Implement a bag of chips for sync.

 The bag of chips is a per-client state used by the server. This state is
stored on the client and send back to the server on all communication.

BUG=None
TEST=None


Review URL: https://chromiumcodereview.appspot.com/10916174

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@156123 0039d316-1c4b-4281-b951-d872f2087c98

12 files changed, 241 insertions, 11 deletions

diff --git a/sync/engine/build_commit_command.cc b/sync/engine/build_commit_command.cc
index 534e196..ade6acb 100644
--- a/sync/engine/build_commit_command.cc
+++ b/sync/engine/build_commit_command.cc
@@ -114,6 +114,8 @@ SyncerError BuildCommitCommand::ExecuteImpl(SyncSession* session) {
   SyncerProtoUtil::SetProtocolVersion(commit_message_);
   SyncerProtoUtil::AddRequestBirthday(
       session->write_transaction()->directory(), commit_message_);
+  SyncerProtoUtil::AddBagOfChips(
+      session->write_transaction()->directory(), commit_message_);
 
   // Cache previously computed position values.  Because |commit_ids|
   // is already in sibling order, we should always hit this map after
diff --git a/sync/engine/download_updates_command.cc b/sync/engine/download_updates_command.cc
index e1ba189..cd0730a 100644
--- a/sync/engine/download_updates_command.cc
+++ b/sync/engine/download_updates_command.cc
@@ -111,6 +111,7 @@ SyncerError DownloadUpdatesCommand::ExecuteImpl(SyncSession* session) {
 
   SyncerProtoUtil::SetProtocolVersion(&client_to_server_message);
   SyncerProtoUtil::AddRequestBirthday(dir, &client_to_server_message);
+  SyncerProtoUtil::AddBagOfChips(dir, &client_to_server_message);
 
   DebugInfo* debug_info = client_to_server_message.mutable_debug_info();
 
diff --git a/sync/engine/syncer_proto_util.cc b/sync/engine/syncer_proto_util.cc
index 8149ad8..eef0208 100644
--- a/sync/engine/syncer_proto_util.cc
+++ b/sync/engine/syncer_proto_util.cc
@@ -163,6 +163,12 @@ void SyncerProtoUtil::AddRequestBirthday(syncable::Directory* dir,
 }
 
 // static
+void SyncerProtoUtil::AddBagOfChips(syncable::Directory* dir,
+                                    ClientToServerMessage* msg) {
+  msg->mutable_bag_of_chips()->ParseFromString(dir->bag_of_chips());
+}
+
+// static
 void SyncerProtoUtil::SetProtocolVersion(ClientToServerMessage* msg) {
   const int current_version =
       ClientToServerMessage::default_instance().protocol_version();
@@ -349,6 +355,8 @@ SyncerError SyncerProtoUtil::PostClientToServerMessage(
   DCHECK(!msg.get_updates().has_requested_types());  // Deprecated.
   DCHECK(msg.has_store_birthday() || IsVeryFirstGetUpdates(msg))
       << "Must call AddRequestBirthday to set birthday.";
+  DCHECK(msg.has_bag_of_chips())
+      << "Must call AddBagOfChips to set bag_of_chips.";
 
   syncable::Directory* dir = session->context()->directory();
 
@@ -371,6 +379,9 @@ SyncerError SyncerProtoUtil::PostClientToServerMessage(
   session->context()->traffic_recorder()->RecordClientToServerResponse(
       *response);
 
+  // Persist a bag of chips if it has been sent by the server.
+  PersistBagOfChips(dir, *response);
+
   SyncProtocolError sync_protocol_error;
 
   // Birthday mismatch overrides any error that is sent by the server.
@@ -509,6 +520,16 @@ const std::string& SyncerProtoUtil::NameFromCommitEntryResponse(
   return entry.name();
 }
 
+// static
+void SyncerProtoUtil::PersistBagOfChips(syncable::Directory* dir,
+    const sync_pb::ClientToServerResponse& response) {
+  if (!response.has_new_bag_of_chips())
+    return;
+  std::string bag_of_chips;
+  if (response.new_bag_of_chips().SerializeToString(&bag_of_chips))
+    dir->set_bag_of_chips(bag_of_chips);
+}
+
 std::string SyncerProtoUtil::SyncEntityDebugString(
     const sync_pb::SyncEntity& entry) {
   const std::string& mtime_str =
diff --git a/sync/engine/syncer_proto_util.h b/sync/engine/syncer_proto_util.h
index b674b50..fab1406 100644
--- a/sync/engine/syncer_proto_util.h
+++ b/sync/engine/syncer_proto_util.h
@@ -74,6 +74,11 @@ class SyncerProtoUtil {
   static const std::string& NameFromCommitEntryResponse(
       const sync_pb::CommitResponse_EntryResponse& entry);
 
+  // Persist the bag of chips if it is present in the response.
+  static void PersistBagOfChips(
+      syncable::Directory* dir,
+      const sync_pb::ClientToServerResponse& response);
+
   // EntitySpecifics is used as a filter for the GetUpdates message to tell
   // the server which datatypes to send back.  This adds a datatype so that
   // it's included in the filter.
@@ -92,6 +97,11 @@ class SyncerProtoUtil {
   static void AddRequestBirthday(syncable::Directory* dir,
                                  sync_pb::ClientToServerMessage* msg);
 
+  // Pull the bag of chips from the dir and put it into the msg.
+  static void AddBagOfChips(syncable::Directory* dir,
+                            sync_pb::ClientToServerMessage* msg);
+
+
   // Set the protocol version field in the outgoing message.
   static void SetProtocolVersion(sync_pb::ClientToServerMessage* msg);
 
diff --git a/sync/protocol/sync.proto b/sync/protocol/sync.proto
index 6d0622b2..5e637ed 100644
--- a/sync/protocol/sync.proto
+++ b/sync/protocol/sync.proto
@@ -463,6 +463,10 @@ message AuthenticateMessage {
   required string auth_token = 1;
 };
 
+// Opaque data used by the server to track the client with.
+message ChipBag {
+};
+
 message ClientToServerMessage {
   required string share = 1;
   optional int32 protocol_version = 2 [default = 31];
@@ -491,6 +495,10 @@ message ClientToServerMessage {
   // This is only sent on the first getupdates of every sync cycle,
   // as an optimization to save bandwidth.
   optional DebugInfo debug_info = 10;
+
+  // Per-client state for use by the server. Sent with every message sent to the
+  // server.
+  optional ChipBag bag_of_chips = 11;
 };
 
 message CommitResponse {
@@ -678,5 +686,9 @@ message ClientToServerResponse {
     repeated int32 error_data_type_ids = 5;
   }
   optional Error error = 13;
+
+  // The new per-client state for this client. If set, should be persisted and
+  // sent with any subsequent ClientToServerMessages.
+  optional ChipBag new_bag_of_chips = 14;
 };
 
diff --git a/sync/syncable/directory.cc b/sync/syncable/directory.cc
index 77979ae..644a4e2 100644
--- a/sync/syncable/directory.cc
+++ b/sync/syncable/directory.cc
@@ -710,6 +710,19 @@ void Directory::set_store_birthday(const string& store_birthday) {
   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 }
 
+string Directory::bag_of_chips() const {
+  ScopedKernelLock lock(this);
+  return kernel_->persisted_info.bag_of_chips;
+}
+
+void Directory::set_bag_of_chips(const string& bag_of_chips) {
+  ScopedKernelLock lock(this);
+  if (kernel_->persisted_info.bag_of_chips == bag_of_chips)
+    return;
+  kernel_->persisted_info.bag_of_chips = bag_of_chips;
+  kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
+}
+
 std::string Directory::GetNotificationState() const {
   ScopedKernelLock lock(this);
   std::string notification_state = kernel_->persisted_info.notification_state;
diff --git a/sync/syncable/directory.h b/sync/syncable/directory.h
index b34882f..49d598c 100644
--- a/sync/syncable/directory.h
+++ b/sync/syncable/directory.h
@@ -170,6 +170,10 @@ class Directory {
     int64 next_id;
     // The persisted notification state.
     std::string notification_state;
+    // The serialized bag of chips we were given by the server. Contents are
+    // opaque to the client. This is the serialization of a message of type
+    // ChipBag defined in sync.proto. It can contains NULL characters.
+    std::string bag_of_chips;
   };
 
   // What the Directory needs on initialization to create itself and its Kernel.
@@ -260,6 +264,11 @@ class Directory {
   std::string store_birthday() const;
   void set_store_birthday(const std::string& store_birthday);
 
+  // (Account) Bag of chip is an opaque state used by the server to track the
+  // client.
+  std::string bag_of_chips() const;
+  void set_bag_of_chips(const std::string& bag_of_chips);
+
   std::string GetNotificationState() const;
   void SetNotificationState(const std::string& notification_state);
 
diff --git a/sync/syncable/directory_backing_store.cc b/sync/syncable/directory_backing_store.cc
index c64c535..9b8e0db 100644
--- a/sync/syncable/directory_backing_store.cc
+++ b/sync/syncable/directory_backing_store.cc
@@ -39,7 +39,7 @@ static const string::size_type kUpdateStatementBufferSize = 2048;
 
 // Increment this version whenever updating DB tables.
 extern const int32 kCurrentDBVersion;  // Global visibility for our unittest.
-const int32 kCurrentDBVersion = 79;
+const int32 kCurrentDBVersion = 80;
 
 // Iterate over the fields of |entry| and bind each to |statement| for
 // updating.  Returns the number of args bound.
@@ -201,11 +201,13 @@ bool DirectoryBackingStore::SaveChanges(
             "UPDATE share_info "
             "SET store_birthday = ?, "
             "next_id = ?, "
-            "notification_state = ?"));
+            "notification_state = ?, "
+            "bag_of_chips = ?"));
     s1.BindString(0, info.store_birthday);
     s1.BindInt64(1, info.next_id);
     s1.BindBlob(2, info.notification_state.data(),
                    info.notification_state.size());
+    s1.BindBlob(3, info.bag_of_chips.data(), info.bag_of_chips.size());
 
     if (!s1.Run())
       return false;
@@ -315,6 +317,12 @@ bool DirectoryBackingStore::InitializeTables() {
       version_on_disk = 79;
   }
 
+  // Version 80 migration is adding the bag_of_chips column.
+  if (version_on_disk == 79) {
+    if (MigrateVersion79To80())
+      version_on_disk = 80;
+  }
+
   // If one of the migrations requested it, drop columns that aren't current.
   // It's only safe to do this after migrating all the way to the current
   // version.
@@ -395,9 +403,10 @@ bool DirectoryBackingStore::RefreshColumns() {
   if (!db_->Execute(
           "INSERT INTO temp_share_info (id, name, store_birthday, "
           "db_create_version, db_create_time, next_id, cache_guid,"
-          "notification_state) "
+          "notification_state, bag_of_chips) "
           "SELECT id, name, store_birthday, db_create_version, "
-          "db_create_time, next_id, cache_guid, notification_state "
+          "db_create_time, next_id, cache_guid, notification_state, "
+          "bag_of_chips "
           "FROM share_info"))
     return false;
 
@@ -429,7 +438,8 @@ bool DirectoryBackingStore::LoadInfo(Directory::KernelLoadInfo* info) {
   {
     sql::Statement s(
         db_->GetUniqueStatement(
-            "SELECT store_birthday, next_id, cache_guid, notification_state "
+            "SELECT store_birthday, next_id, cache_guid, notification_state, "
+            "bag_of_chips "
             "FROM share_info"));
     if (!s.Step())
       return false;
@@ -438,6 +448,7 @@ bool DirectoryBackingStore::LoadInfo(Directory::KernelLoadInfo* info) {
     info->kernel_info.next_id = s.ColumnInt64(1);
     info->cache_guid = s.ColumnString(2);
     s.ColumnBlobAsString(3, &(info->kernel_info.notification_state));
+    s.ColumnBlobAsString(4, &(info->kernel_info.bag_of_chips));
 
     // Verify there was only one row returned.
     DCHECK(!s.Step());
@@ -957,6 +968,19 @@ bool DirectoryBackingStore::MigrateVersion78To79() {
   SetVersion(79);
   return true;
 }
+bool DirectoryBackingStore::MigrateVersion79To80() {
+  if (!db_->Execute(
+          "ALTER TABLE share_info ADD COLUMN bag_of_chips BLOB"))
+    return false;
+  sql::Statement update(db_->GetUniqueStatement(
+          "UPDATE share_info SET bag_of_chips = ?"));
+  // An empty message is serialized to an empty string.
+  update.BindBlob(0, NULL, 0);
+  if (!update.Run())
+    return false;
+  SetVersion(80);
+  return true;
+}
 
 bool DirectoryBackingStore::CreateTables() {
   DVLOG(1) << "First run, creating tables";
@@ -992,7 +1016,8 @@ bool DirectoryBackingStore::CreateTables() {
             "?, "   // db_create_time
             "-2, "  // next_id
             "?, "   // cache_guid
-            "?);"));  // notification_state
+            "?, "   // notification_state
+            "?);"));  // bag_of_chips
     s.BindString(0, dir_name_);                   // id
     s.BindString(1, dir_name_);                   // name
     s.BindString(2, "");                          // store_birthday
@@ -1002,7 +1027,7 @@ bool DirectoryBackingStore::CreateTables() {
     s.BindInt(4, static_cast<int32>(time(0)));    // db_create_time
     s.BindString(5, GenerateCacheGUID());         // cache_guid
     s.BindBlob(6, NULL, 0);                       // notification_state
-
+    s.BindBlob(7, NULL, 0);                       // bag_of_chips
     if (!s.Run())
       return false;
   }
@@ -1078,10 +1103,10 @@ bool DirectoryBackingStore::CreateShareInfoTable(bool is_temporary) {
       "db_create_version TEXT, "
       "db_create_time INT, "
       "next_id INT default -2, "
-      "cache_guid TEXT ");
-
-  query.append(", notification_state BLOB");
-  query.append(")");
+      "cache_guid TEXT, "
+      "notification_state BLOB, "
+      "bag_of_chips BLOB"
+      ")");
   return db_->Execute(query.c_str());
 }
 
diff --git a/sync/syncable/directory_backing_store.h b/sync/syncable/directory_backing_store.h
index 054c4d5..a441a86 100644
--- a/sync/syncable/directory_backing_store.h
+++ b/sync/syncable/directory_backing_store.h
@@ -154,6 +154,7 @@ class DirectoryBackingStore : public base::NonThreadSafe {
   bool MigrateVersion76To77();
   bool MigrateVersion77To78();
   bool MigrateVersion78To79();
+  bool MigrateVersion79To80();
 
   scoped_ptr<sql::Connection> db_;
   sql::Statement save_entry_statement_;
diff --git a/sync/syncable/directory_backing_store_unittest.cc b/sync/syncable/directory_backing_store_unittest.cc
index affddbf..1864ba9 100644
--- a/sync/syncable/directory_backing_store_unittest.cc
+++ b/sync/syncable/directory_backing_store_unittest.cc
@@ -62,6 +62,7 @@ class MigrationTest : public testing::TestWithParam<int> {
   void SetUpVersion76Database(sql::Connection* connection);
   void SetUpVersion77Database(sql::Connection* connection);
   void SetUpVersion78Database(sql::Connection* connection);
+  void SetUpVersion79Database(sql::Connection* connection);
 
   void SetUpCurrentDatabaseAndCheckVersion(sql::Connection* connection) {
     SetUpVersion77Database(connection);  // Prepopulates data.
@@ -1629,6 +1630,101 @@ void MigrationTest::SetUpVersion78Database(sql::Connection* connection) {
   ASSERT_TRUE(connection->CommitTransaction());
 }
 
+void MigrationTest::SetUpVersion79Database(sql::Connection* connection) {
+  ASSERT_TRUE(connection->is_open());
+  ASSERT_TRUE(connection->BeginTransaction());
+  ASSERT_TRUE(connection->Execute(
+      "CREATE TABLE share_version (id VARCHAR(128) primary key, data INT);"
+      "INSERT INTO 'share_version' VALUES('nick@chromium.org',78);"
+      "CREATE TABLE models (model_id BLOB primary key, progress_marker BLOB, in"
+          "itial_sync_ended BOOLEAN default 0);"
+      "INSERT INTO 'models' VALUES(X'C2881000',X'0888810218B605',1);"
+      "CREATE TABLE 'metas'(metahandle bigint primary key ON CONFLICT FAIL,base"
+          "_version bigint default -1,server_version bigint default 0,server_po"
+          "sition_in_parent bigint default 0,local_external_id bigint default 0"
+          ",mtime bigint default 0,server_mtime bigint default 0,ctime bigint d"
+          "efault 0,server_ctime bigint default 0,id varchar(255) default 'r',p"
+          "arent_id varchar(255) default 'r',server_parent_id varchar(255) defa"
+          "ult 'r',prev_id varchar(255) default 'r',next_id varchar(255) defaul"
+          "t 'r',is_unsynced bit default 0,is_unapplied_update bit default 0,is"
+          "_del bit default 0,is_dir bit default 0,server_is_dir bit default 0,"
+          "server_is_del bit default 0,non_unique_name varchar,server_non_uniqu"
+          "e_name varchar(255),unique_server_tag varchar,unique_client_tag varc"
+          "har,specifics blob,server_specifics blob, base_server_specifics BLOB"
+          ");"
+      "INSERT INTO 'metas' VALUES(1,-1,0,0,0," META_PROTO_TIMES_VALS(1) ",'r','"
+          "r','r','r','r',0,0,0,1,0,0,NULL,NULL,NULL,NULL,X'',X'',NULL);"
+      "INSERT INTO 'metas' VALUES(2,669,669,-2097152,4,"
+          META_PROTO_TIMES_VALS(2) ",'s_ID_2','s_ID_9','s_ID_9','s_ID_2','s_ID_"
+          "2',0,0,1,0,0,1,'Deleted Item','Deleted Item',NULL,NULL,X'C28810220A1"
+          "6687474703A2F2F7777772E676F6F676C652E636F6D2F12084141534741534741',X"
+          "'C28810260A17687474703A2F2F7777772E676F6F676C652E636F6D2F32120B41534"
+          "14447414447414447',NULL);"
+      "INSERT INTO 'metas' VALUES(4,681,681,-3145728,3,"
+          META_PROTO_TIMES_VALS(4) ",'s_ID_4','s_ID_9','s_ID_9','s_ID_4','s_ID_"
+          "4',0,0,1,0,0,1,'Welcome to Chromium','Welcome to Chromium',NULL,NULL"
+          ",X'C28810350A31687474703A2F2F7777772E676F6F676C652E636F6D2F6368726F6"
+          "D652F696E746C2F656E2F77656C636F6D652E68746D6C1200',X'C28810350A31687"
+          "474703A2F2F7777772E676F6F676C652E636F6D2F6368726F6D652F696E746C2F656"
+          "E2F77656C636F6D652E68746D6C1200',NULL);"
+      "INSERT INTO 'metas' VALUES(5,677,677,1048576,7,"
+          META_PROTO_TIMES_VALS(5) ",'s_ID_5','s_ID_9','s_ID_9','s_ID_5','s_ID_"
+          "5',0,0,1,0,0,1,'Google','Google',NULL,NULL,X'C28810220A16687474703A2"
+          "F2F7777772E676F6F676C652E636F6D2F12084147415347415347',X'C28810220A1"
+          "6687474703A2F2F7777772E676F6F676C652E636F6D2F12084147464447415347',N"
+          "ULL);"
+      "INSERT INTO 'metas' VALUES(6,694,694,-4194304,6,"
+          META_PROTO_TIMES_VALS(6) ",'s_ID_6','s_ID_9','s_ID_9','r','r',0,0,0,1"
+          ",1,0,'The Internet','The Internet',NULL,NULL,X'C2881000',X'C2881000'"
+          ",NULL);"
+      "INSERT INTO 'metas' VALUES(7,663,663,1048576,0,"
+          META_PROTO_TIMES_VALS(7) ",'s_ID_7','r','r','r','r',0,0,0,1,1,0,'Goog"
+          "le Chrome','Google Chrome','google_chrome',NULL,NULL,NULL,NULL);"
+      "INSERT INTO 'metas' VALUES(8,664,664,1048576,0,"
+          META_PROTO_TIMES_VALS(8) ",'s_ID_8','s_ID_7','s_ID_7','r','r',0,0,0,1"
+          ",1,0,'Bookmarks','Bookmarks','google_chrome_bookmarks',NULL,X'C28810"
+          "00',X'C2881000',NULL);"
+      "INSERT INTO 'metas' VALUES(9,665,665,1048576,1,"
+          META_PROTO_TIMES_VALS(9) ",'s_ID_9','s_ID_8','s_ID_8','r','s_ID_10',0"
+          ",0,0,1,1,0,'Bookmark Bar','Bookmark Bar','bookmark_bar',NULL,X'C2881"
+          "000',X'C2881000',NULL);"
+      "INSERT INTO 'metas' VALUES(10,666,666,2097152,2,"
+          META_PROTO_TIMES_VALS(10) ",'s_ID_10','s_ID_8','s_ID_8','s_ID_9','r',"
+          "0,0,0,1,1,0,'Other Bookmarks','Other Bookmarks','other_bookmarks',NU"
+          "LL,X'C2881000',X'C2881000',NULL);"
+      "INSERT INTO 'metas' VALUES(11,683,683,-1048576,8,"
+          META_PROTO_TIMES_VALS(11) ",'s_ID_11','s_ID_6','s_ID_6','r','s_ID_13'"
+          ",0,0,0,0,0,0,'Home (The Chromium Projects)','Home (The Chromium Proj"
+          "ects)',NULL,NULL,X'C28810220A18687474703A2F2F6465762E6368726F6D69756"
+          "D2E6F72672F1206414741545741',X'C28810290A1D687474703A2F2F6465762E636"
+          "8726F6D69756D2E6F72672F6F7468657212084146414756415346',NULL);"
+      "INSERT INTO 'metas' VALUES(12,685,685,0,9,"
+          META_PROTO_TIMES_VALS(12) ",'s_ID_12','s_ID_6','s_ID_6','s_ID_13','s_"
+          "ID_14',0,0,0,1,1,0,'Extra Bookmarks','Extra Bookmarks',NULL,NULL,X'C"
+          "2881000',X'C2881000',NULL);"
+      "INSERT INTO 'metas' VALUES(13,687,687,-917504,10,"
+          META_PROTO_TIMES_VALS(13) ",'s_ID_13','s_ID_6','s_ID_6','s_ID_11','s_"
+          "ID_12',0,0,0,0,0,0,'ICANN | Internet Corporation for Assigned Names "
+          "and Numbers','ICANN | Internet Corporation for Assigned Names and Nu"
+          "mbers',NULL,NULL,X'C28810240A15687474703A2F2F7777772E6963616E6E2E636"
+          "F6D2F120B504E474158463041414646',X'C28810200A15687474703A2F2F7777772"
+          "E6963616E6E2E636F6D2F120744414146415346',NULL);"
+      "INSERT INTO 'metas' VALUES(14,692,692,1048576,11,"
+          META_PROTO_TIMES_VALS(14) ",'s_ID_14','s_ID_6','s_ID_6','s_ID_12','r'"
+          ",0,0,0,0,0,0,'The WebKit Open Source Project','The WebKit Open Sourc"
+          "e Project',NULL,NULL,X'C288101A0A12687474703A2F2F7765626B69742E6F726"
+          "72F1204504E4758',X'C288101C0A13687474703A2F2F7765626B69742E6F72672F7"
+          "81205504E473259',NULL);"
+      "CREATE TABLE 'share_info' (id TEXT primary key, name TEXT, store_birthda"
+          "y TEXT, db_create_version TEXT, db_create_time INT, next_id INT defa"
+          "ult -2, cache_guid TEXT , notification_state BLOB);"
+      "INSERT INTO 'share_info' VALUES('nick@chromium.org','nick@chromium.org',"
+          "'c27e9f59-08ca-46f8-b0cc-f16a2ed778bb','Unknown',1263522064,"
+          "-131078,'9010788312004066376x-6609234393368420856x',NULL);"
+          ));
+  ASSERT_TRUE(connection->CommitTransaction());
+}
+
 TEST_F(DirectoryBackingStoreTest, MigrateVersion67To68) {
   sql::Connection connection;
   ASSERT_TRUE(connection.OpenInMemory());
@@ -1958,6 +2054,31 @@ TEST_F(DirectoryBackingStoreTest, MigrateVersion78To79) {
   EXPECT_LE(load_info.kernel_info.next_id, kInitialNextId - 65536);
 }
 
+TEST_F(DirectoryBackingStoreTest, MigrateVersion79To80) {
+  sql::Connection connection;
+  ASSERT_TRUE(connection.OpenInMemory());
+  SetUpVersion79Database(&connection);
+
+  scoped_ptr<TestDirectoryBackingStore> dbs(
+      new TestDirectoryBackingStore(GetUsername(), &connection));
+  ASSERT_FALSE(dbs->needs_column_refresh_);
+  ASSERT_TRUE(dbs->MigrateVersion79To80());
+  ASSERT_EQ(80, dbs->GetVersion());
+  ASSERT_FALSE(dbs->needs_column_refresh_);
+
+  // Ensure the bag_of_chips has been set.
+  MetahandlesIndex entry_bucket;
+  STLElementDeleter<MetahandlesIndex> deleter(&entry_bucket);
+  Directory::KernelLoadInfo load_info;
+
+  ASSERT_TRUE(dbs->Load(&entry_bucket, &load_info));
+  // Check that the initial value is the serialization of an empty ChipBag.
+  sync_pb::ChipBag chip_bag;
+  std::string serialized_chip_bag;
+  ASSERT_TRUE(chip_bag.SerializeToString(&serialized_chip_bag));
+  EXPECT_EQ(serialized_chip_bag, load_info.kernel_info.bag_of_chips);
+}
+
 TEST_P(MigrationTest, ToCurrentVersion) {
   sql::Connection connection;
   ASSERT_TRUE(connection.OpenInMemory());
@@ -1998,6 +2119,9 @@ TEST_P(MigrationTest, ToCurrentVersion) {
     case 78:
       SetUpVersion78Database(&connection);
       break;
+    case 79:
+      SetUpVersion79Database(&connection);
+      break;
     default:
       // If you see this error, it may mean that you've increased the
       // database version number but you haven't finished adding unit tests
diff --git a/sync/syncable/syncable_unittest.cc b/sync/syncable/syncable_unittest.cc
index b74d41c..f69347b 100644
--- a/sync/syncable/syncable_unittest.cc
+++ b/sync/syncable/syncable_unittest.cc
@@ -1583,15 +1583,24 @@ TEST_F(OnDiskSyncableDirectoryTest, TestShareInfo) {
   dir_->set_initial_sync_ended_for_type(AUTOFILL, true);
   dir_->set_store_birthday("Jan 31st");
   dir_->SetNotificationState("notification_state");
+  const char* const bag_of_chips_array = "\0bag of chips";
+  const std::string bag_of_chips_string =
+      std::string(bag_of_chips_array, sizeof(bag_of_chips_array));
+  dir_->set_bag_of_chips(bag_of_chips_string);
   {
     ReadTransaction trans(FROM_HERE, dir_.get());
     EXPECT_TRUE(dir_->initial_sync_ended_for_type(AUTOFILL));
     EXPECT_FALSE(dir_->initial_sync_ended_for_type(BOOKMARKS));
     EXPECT_EQ("Jan 31st", dir_->store_birthday());
     EXPECT_EQ("notification_state", dir_->GetNotificationState());
+    EXPECT_EQ(bag_of_chips_string, dir_->bag_of_chips());
   }
   dir_->set_store_birthday("April 10th");
   dir_->SetNotificationState("notification_state2");
+  const char* const bag_of_chips2_array = "\0bag of chips2";
+  const std::string bag_of_chips2_string =
+      std::string(bag_of_chips2_array, sizeof(bag_of_chips2_array));
+  dir_->set_bag_of_chips(bag_of_chips2_string);
   dir_->SaveChanges();
   {
     ReadTransaction trans(FROM_HERE, dir_.get());
@@ -1599,6 +1608,7 @@ TEST_F(OnDiskSyncableDirectoryTest, TestShareInfo) {
     EXPECT_FALSE(dir_->initial_sync_ended_for_type(BOOKMARKS));
     EXPECT_EQ("April 10th", dir_->store_birthday());
     EXPECT_EQ("notification_state2", dir_->GetNotificationState());
+    EXPECT_EQ(bag_of_chips2_string, dir_->bag_of_chips());
   }
   dir_->SetNotificationState("notification_state2");
   // Restore the directory from disk.  Make sure that nothing's changed.
@@ -1609,6 +1619,7 @@ TEST_F(OnDiskSyncableDirectoryTest, TestShareInfo) {
     EXPECT_FALSE(dir_->initial_sync_ended_for_type(BOOKMARKS));
     EXPECT_EQ("April 10th", dir_->store_birthday());
     EXPECT_EQ("notification_state2", dir_->GetNotificationState());
+    EXPECT_EQ(bag_of_chips2_string, dir_->bag_of_chips());
   }
 }
 
diff --git a/sync/test/test_directory_backing_store.h b/sync/test/test_directory_backing_store.h
index f6b0322..612e728 100644
--- a/sync/test/test_directory_backing_store.h
+++ b/sync/test/test_directory_backing_store.h
@@ -41,6 +41,7 @@ class TestDirectoryBackingStore : public DirectoryBackingStore {
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, MigrateVersion76To77);
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, MigrateVersion77To78);
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, MigrateVersion78To79);
+  FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, MigrateVersion79To80);
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, ModelTypeIds);
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, Corruption);
   FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest, DeleteEntries);