[USS] Implement ApplySyncChanges and OnURLVisited/Modified/Deleted.

components/history/core/browser/typed_url_sync_bridge_unittest.cc

Index: components/history/core/browser/typed_url_sync_bridge_unittest.cc
diff --git a/components/history/core/browser/typed_url_sync_bridge_unittest.cc b/components/history/core/browser/typed_url_sync_bridge_unittest.cc
index 4a36d3aca536b3f152cbd48166ddb3955b99e1ab..e598864298f05885c687647202797e69de33a01d 100644
--- a/components/history/core/browser/typed_url_sync_bridge_unittest.cc
+++ b/components/history/core/browser/typed_url_sync_bridge_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "components/history/core/browser/typed_url_sync_bridge.h"
 
+#include "base/big_endian.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ -26,12 +27,19 @@ using syncer::EntityData;
 using syncer::EntityDataPtr;
 using syncer::KeyAndData;
 using syncer::MetadataBatch;
+using syncer::MetadataChangeList;
 using syncer::RecordingModelTypeChangeProcessor;
 
 namespace history {
 
 namespace {
 
+// Constants used to limit size of visits processed. See
+// equivalent constants in typed_url_sync_bridge.cc for descriptions.
+const int kMaxTypedUrlVisits = 100;
+const int kVisitThrottleThreshold = 10;
+const int kVisitThrottleMultiple = 10;
+
 // Visits with this timestamp are treated as expired.
 const int kExpiredVisit = -1;
 
@@ -41,6 +49,49 @@ const char kTitle2[] = "cookie";
 const char kURL[] = "http://pie.com/";
 const char kURL2[] = "http://cookie.com/";
 
+bool URLsEqual(URLRow& row, sync_pb::TypedUrlSpecifics& specifics) {
+  return ((row.url().spec().compare(specifics.url()) == 0) &&
+          (base::UTF16ToUTF8(row.title()).compare(specifics.title()) == 0) &&
+          (row.hidden() == specifics.hidden()));
+}
+
+bool URLsEqual(URLRow& lhs, URLRow& rhs) {
+  // Only compare synced fields (ignore typed_count and visit_count as those
+  // are maintained by the history subsystem).
+  return (lhs.url().spec().compare(rhs.url().spec()) == 0) &&
+         (lhs.title().compare(rhs.title()) == 0) &&
+         (lhs.hidden() == rhs.hidden());
+}
+
+void AddNewestVisit(ui::PageTransition transition,
+                    int64_t visit_time,
+                    URLRow* url,
+                    VisitVector* visits) {
+  base::Time time = base::Time::FromInternalValue(visit_time);
+  visits->insert(visits->begin(), VisitRow(url->id(), time, 0, transition, 0));
+
+  if (ui::PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_TYPED)) {
+    url->set_typed_count(url->typed_count() + 1);
+  }
+
+  url->set_last_visit(time);
+  url->set_visit_count(visits->size());
+}
+
+void AddOldestVisit(ui::PageTransition transition,
+                    int64_t visit_time,
+                    URLRow* url,
+                    VisitVector* visits) {
+  base::Time time = base::Time::FromInternalValue(visit_time);
+  visits->push_back(VisitRow(url->id(), time, 0, transition, 0));
+
+  if (ui::PageTransitionCoreTypeIs(transition, ui::PAGE_TRANSITION_TYPED)) {
+    url->set_typed_count(url->typed_count() + 1);
+  }
+
+  url->set_visit_count(visits->size());
+}
+
 // Create a new row object and the typed visit çorresponding with the time at
 // |last_visit| in the |visits| vector.
 URLRow MakeTypedUrlRow(const std::string& url,
@@ -104,6 +155,12 @@ void VerifyDataBatch(std::map<std::string, TypedUrlSpecifics> expected,
   EXPECT_TRUE(expected.empty());
 }
 
+std::string IntToStroageKey(int id) {
+  std::string storage_key(sizeof(URLID), 0);
+  base::WriteBigEndian<URLID>(&storage_key[0], id);
+  return storage_key;
+}
+
 class TestHistoryBackendDelegate : public HistoryBackend::Delegate {
  public:
   TestHistoryBackendDelegate() {}
@@ -149,16 +206,17 @@ class TestHistoryBackend : public HistoryBackend {
   }
 
   void SetVisitsForUrl(URLRow& new_url, const VisitVector visits) {
-    std::vector<history::VisitInfo> added_visits;
-    URLRows new_urls;
-    DeleteURL(new_url.url());
+    if (!GetURL(new_url.url(), nullptr)) {
+      URLRows new_urls;
+      new_urls.push_back(new_url);
+      AddPagesWithDetails(new_urls, SOURCE_SYNCED);
+    }
+
+    std::vector<VisitInfo> added_visits;
     for (const auto& visit : visits) {
-      added_visits.push_back(
-          history::VisitInfo(visit.visit_time, visit.transition));
+      added_visits.push_back(VisitInfo(visit.visit_time, visit.transition));
     }
-    new_urls.push_back(new_url);
-    AddPagesWithDetails(new_urls, history::SOURCE_SYNCED);
-    AddVisits(new_url.url(), added_visits, history::SOURCE_SYNCED);
+    AddVisits(new_url.url(), added_visits, SOURCE_SYNCED);
     new_url.set_id(GetIdByUrl(new_url.url()));
   }
 
@@ -189,7 +247,10 @@ class TypedURLSyncBridgeTest : public testing::Test {
     fake_history_backend_->SetTypedURLSyncBridgeForTest(std::move(bridge));
   }
 
-  void TearDown() override { fake_history_backend_->Closing(); }
+  void TearDown() override {
+    VerifyProcessorReceivedValidEntityData();
+    fake_history_backend_->Closing();
+  }
 
   // Starts sync for |typed_url_sync_bridge_| with |initial_data| as the
   // initial sync data.
@@ -202,6 +263,80 @@ class TypedURLSyncBridgeTest : public testing::Test {
     EXPECT_FALSE(error);
   }
 
+  bool BuildAndPushLocalChanges(unsigned int num_typed_urls,
+                                unsigned int num_reload_urls,
+                                const std::vector<std::string>& urls,
+                                URLRows* rows,
+                                std::vector<VisitVector>* visit_vectors) {
+    unsigned int total_urls = num_typed_urls + num_reload_urls;
+    DCHECK(urls.size() >= total_urls);
+    if (!bridge())
+      return false;
+
+    if (total_urls) {
+      // Create new URL rows, populate the mock backend with its visits, and
+      // send to the sync service.
+      URLRows changed_urls;
+
+      for (unsigned int i = 0; i < total_urls; ++i) {
+        int typed = i < num_typed_urls ? 1 : 0;
+        VisitVector visits;
+        visit_vectors->push_back(visits);
+        rows->push_back(MakeTypedUrlRow(urls[i], kTitle, typed, i + 3, false,
+                                        &visit_vectors->back()));
+        fake_history_backend_->SetVisitsForUrl(rows->back(),
+                                               visit_vectors->back());
+        changed_urls.push_back(rows->back());
+      }
+
+      bridge()->OnURLsModified(fake_history_backend_.get(), changed_urls);
+    }
+
+    // Check that communication with sync was successful.
+    if (num_typed_urls != processor().put_multimap().size())
+      return false;
+    return true;
+  }
+
+  VisitVector ApplyUrlAndVisitsChange(const std::string& url,
+                                      const std::string& title,
+                                      int typed_count,
+                                      int64_t last_visit,
+                                      bool hidden,
+                                      EntityChange::ChangeType change_type) {
+    VisitVector visits;
+    URLRow row =
+        MakeTypedUrlRow(url, title, typed_count, last_visit, hidden, &visits);
+    sync_pb::TypedUrlSpecifics typed_url_specifics;
+    WriteToTypedUrlSpecifics(row, visits, &typed_url_specifics);
+    std::unique_ptr<MetadataChangeList> metadata_changes =
+        bridge()->CreateMetadataChangeList();
+    EntityChangeList entity_changes;
+    switch (change_type) {
+      case EntityChange::ACTION_ADD:
+        entity_changes.push_back(EntityChange::CreateAdd(
+            std::string(), SpecificsToEntity(typed_url_specifics)));
+        break;
+      case EntityChange::ACTION_UPDATE:
+        entity_changes.push_back(
+            EntityChange::CreateUpdate(GetStorageKey(typed_url_specifics.url()),
+                                       SpecificsToEntity(typed_url_specifics)));
+        break;
+      case EntityChange::ACTION_DELETE:
+        entity_changes.push_back(EntityChange::CreateDelete(
+            GetStorageKey(typed_url_specifics.url())));
+        break;
+    }
+    bridge()->ApplySyncChanges(std::move(metadata_changes), entity_changes);
+    return visits;
+  }
+
+  void AddObserver() {
+    bridge()->history_backend_observer_.Add(fake_history_backend_.get());
+  }
+
+  void RemoveObserver() { bridge()->history_backend_observer_.RemoveAll(); }
+
   // Fills |specifics| with the sync data for |url| and |visits|.
   static bool WriteToTypedUrlSpecifics(const URLRow& url,
                                        const VisitVector& visits,
@@ -209,9 +344,8 @@ class TypedURLSyncBridgeTest : public testing::Test {
     return TypedURLSyncBridge::WriteToTypedUrlSpecifics(url, visits, specifics);
   }
 
-  std::string GetStorageKey(const TypedUrlSpecifics& specifics) {
-    std::string key = bridge()->GetStorageKeyInternal(specifics.url());
-    return key;
+  std::string GetStorageKey(const std::string& url) {
+    return bridge()->GetStorageKeyInternal(url);
   }
 
   EntityDataPtr SpecificsToEntity(const TypedUrlSpecifics& specifics) {
@@ -226,7 +360,7 @@ class TypedURLSyncBridgeTest : public testing::Test {
     EntityChangeList entity_change_list;
     for (const auto& specifics : specifics_vector) {
       entity_change_list.push_back(EntityChange::CreateAdd(
-          GetStorageKey(specifics), SpecificsToEntity(specifics)));
+          GetStorageKey(specifics.url()), SpecificsToEntity(specifics)));
     }
     return entity_change_list;
   }
@@ -235,15 +369,86 @@ class TypedURLSyncBridgeTest : public testing::Test {
       const std::vector<TypedUrlSpecifics>& specifics_vector) {
     std::map<std::string, TypedUrlSpecifics> map;
     for (const auto& specifics : specifics_vector) {
-      map[GetStorageKey(specifics)] = specifics;
+      map[GetStorageKey(specifics.url())] = specifics;
     }
     return map;
   }
 
-  void VerifyLocalHistoryData(const std::vector<TypedUrlSpecifics>& expected) {
+  void VerifyAllLocalHistoryData(
+      const std::vector<TypedUrlSpecifics>& expected) {
     bridge()->GetAllData(base::Bind(&VerifyDataBatch, ExpectedMap(expected)));
   }
 
+  void VerifyGetData(TypedURLSyncBridge::StorageKeyList storage_keys,
+                     const std::vector<TypedUrlSpecifics>& expected) {
+    bridge()->GetData(storage_keys,
+                      base::Bind(&VerifyDataBatch, ExpectedMap(expected)));
+  }
+
+  void VerifyProcessorReceivedValidEntityData() {
+    for (const auto& it : processor().put_multimap()) {
+      EXPECT_GT(TypedURLSyncMetadataDatabase::StorageKeyToURLID(it.first), 0);
+      EXPECT_TRUE(it.second->specifics.has_typed_url());
+    }
+  }
+
+  sync_pb::TypedUrlSpecifics GetLastUpdateForURL(const std::string& url) {
+    const std::string storage_key = GetStorageKey(url);
+    auto eq_range = processor().put_multimap().equal_range(storage_key);
+    if (eq_range.first == eq_range.second)
+      return sync_pb::TypedUrlSpecifics();
+
+    auto recorded_specifics_iterator = --eq_range.second;
+    EXPECT_NE(processor().put_multimap().end(), recorded_specifics_iterator);
+    EXPECT_TRUE(recorded_specifics_iterator->second->specifics.has_typed_url());
+
+    return recorded_specifics_iterator->second->specifics.typed_url();
+  }
+
+  static void DiffVisits(const VisitVector& history_visits,
+                         const sync_pb::TypedUrlSpecifics& sync_specifics,
+                         std::vector<VisitInfo>* new_visits,
+                         VisitVector* removed_visits) {
+    TypedURLSyncBridge::DiffVisits(history_visits, sync_specifics, new_visits,
+                                   removed_visits);
+  }
+
+  static VisitRow CreateVisit(ui::PageTransition type, int64_t timestamp) {
+    return VisitRow(0, base::Time::FromInternalValue(timestamp), 0, type, 0);
+  }
+
+  static TypedURLSyncBridge::MergeResult MergeUrls(
+      const sync_pb::TypedUrlSpecifics& typed_url,
+      const URLRow& url,
+      VisitVector* visits,
+      URLRow* new_url,
+      std::vector<VisitInfo>* new_visits) {
+    return TypedURLSyncBridge::MergeUrls(typed_url, url, visits, new_url,
+                                         new_visits);
+  }
+
+  static sync_pb::TypedUrlSpecifics MakeTypedUrlSpecifics(const char* url,
+                                                          const char* title,
+                                                          int64_t last_visit,
+                                                          bool hidden) {
+    sync_pb::TypedUrlSpecifics typed_url;
+    typed_url.set_url(url);
+    typed_url.set_title(title);
+    typed_url.set_hidden(hidden);
+    typed_url.add_visits(last_visit);
+    typed_url.add_visit_transitions(ui::PAGE_TRANSITION_TYPED);
+    return typed_url;
+  }
+
+  static const TypedURLSyncBridge::MergeResult DIFF_NONE =
+      TypedURLSyncBridge::DIFF_NONE;
+  static const TypedURLSyncBridge::MergeResult DIFF_UPDATE_NODE =
+      TypedURLSyncBridge::DIFF_UPDATE_NODE;
+  static const TypedURLSyncBridge::MergeResult DIFF_LOCAL_ROW_CHANGED =
+      TypedURLSyncBridge::DIFF_LOCAL_ROW_CHANGED;
+  static const TypedURLSyncBridge::MergeResult DIFF_LOCAL_VISITS_ADDED =
+      TypedURLSyncBridge::DIFF_LOCAL_VISITS_ADDED;
+
   TypedURLSyncBridge* bridge() { return typed_url_sync_bridge_; }
 
   TypedURLSyncMetadataDatabase* metadata_store() {
@@ -277,7 +482,26 @@ TEST_F(TypedURLSyncBridgeTest, GetAllData) {
   WriteToTypedUrlSpecifics(row2, visits2, &typed_url2);
 
   // Check that the local cache is still correct.
-  VerifyLocalHistoryData({typed_url1, typed_url2});
+  VerifyAllLocalHistoryData({typed_url1, typed_url2});
+}
+
+// Add two typed urls locally and verify bridge can get them from GetData.
+TEST_F(TypedURLSyncBridgeTest, GetData) {
+  // Add two urls to backend.
+  VisitVector visits1, visits2;
+  URLRow row1 = MakeTypedUrlRow(kURL, kTitle, 1, 3, false, &visits1);
+  URLRow row2 = MakeTypedUrlRow(kURL2, kTitle2, 2, 4, false, &visits2);
+  fake_history_backend_->SetVisitsForUrl(row1, visits1);
+  fake_history_backend_->SetVisitsForUrl(row2, visits2);
+
+  // Create the same data in sync.
+  TypedUrlSpecifics typed_url1, typed_url2;
+  WriteToTypedUrlSpecifics(row1, visits1, &typed_url1);
+  WriteToTypedUrlSpecifics(row2, visits2, &typed_url2);
+
+  // Check that the local cache is still correct.
+  VerifyGetData({IntToStroageKey(1)}, {typed_url1});
+  VerifyGetData({IntToStroageKey(2)}, {typed_url2});
 }
 
 // Add a typed url locally and one to sync with the same data. Starting sync
@@ -296,8 +520,19 @@ TEST_F(TypedURLSyncBridgeTest, MergeUrlNoChange) {
   StartSyncing({*typed_url});
   EXPECT_TRUE(processor().put_multimap().empty());
 
+  // Even Sync already know the url, bridge still need to tell sync about
+  // storage keys.
+  EXPECT_EQ(1u, processor().update_multimap().size());
+
+  // Verify processor receive correct upate storage key.
+  const auto& it = processor().update_multimap().begin();
+  EXPECT_EQ(it->first, IntToStroageKey(1));
+  EXPECT_TRUE(it->second->specifics.has_typed_url());
+  EXPECT_EQ(it->second->specifics.typed_url().url(), kURL);
+  EXPECT_EQ(it->second->specifics.typed_url().title(), kTitle);
+
   // Check that the local cache was is still correct.
-  VerifyLocalHistoryData({*typed_url});
+  VerifyAllLocalHistoryData({*typed_url});
 }
 
 // Add a corupted typed url locally, has typed url count 1, but no real typed
@@ -332,12 +567,12 @@ TEST_F(TypedURLSyncBridgeTest, MergeUrlEmptySync) {
   sync_pb::EntitySpecifics entity_specifics;
   sync_pb::TypedUrlSpecifics* typed_url = entity_specifics.mutable_typed_url();
   WriteToTypedUrlSpecifics(row, visits, typed_url);
-  VerifyLocalHistoryData({*typed_url});
+  VerifyAllLocalHistoryData({*typed_url});
 
   // Check that the server was updated correctly.
   ASSERT_EQ(1U, processor().put_multimap().size());
   auto recorded_specifics_iterator =
-      processor().put_multimap().find(GetStorageKey(*typed_url));
+      processor().put_multimap().find(GetStorageKey(typed_url->url()));
   EXPECT_NE(processor().put_multimap().end(), recorded_specifics_iterator);
   TypedUrlSpecifics recorded_specifics =
       recorded_specifics_iterator->second->specifics.typed_url();
@@ -361,6 +596,14 @@ TEST_F(TypedURLSyncBridgeTest, MergeUrlEmptyLocal) {
 
   StartSyncing({*typed_url});
   EXPECT_EQ(0u, processor().put_multimap().size());
+  EXPECT_EQ(1u, processor().update_multimap().size());
+
+  // Verify processor receive correct upate storage key.
+  const auto& it = processor().update_multimap().begin();
+  EXPECT_EQ(it->first, IntToStroageKey(1));
+  EXPECT_TRUE(it->second->specifics.has_typed_url());
+  EXPECT_EQ(it->second->specifics.typed_url().url(), kURL);
+  EXPECT_EQ(it->second->specifics.typed_url().title(), kTitle);
 
   // Check that the backend was updated correctly.
   VisitVector all_visits;
@@ -374,6 +617,129 @@ TEST_F(TypedURLSyncBridgeTest, MergeUrlEmptyLocal) {
       all_visits[0].transition, visits[0].transition));
 }
 
+// Add a url to the local and sync data before sync begins, with the sync data
+// having more recent visits. Check that starting sync updates the backend
+// with the sync visit, while the older local visit is not pushed to sync.
+// The title should be updated to the sync version due to the more recent
+// timestamp.
+TEST_F(TypedURLSyncBridgeTest, MergeUrlOldLocal) {
+  // Add a url to backend.
+  VisitVector visits;
+  URLRow local_row = MakeTypedUrlRow(kURL, kTitle, 1, 3, false, &visits);
+  fake_history_backend_->SetVisitsForUrl(local_row, visits);
+
+  // Create sync data for the same url with a more recent visit.
+  VisitVector server_visits;
+  URLRow server_row =
+      MakeTypedUrlRow(kURL, kTitle2, 1, 6, false, &server_visits);
+  server_row.set_id(fake_history_backend_->GetIdByUrl(GURL(kURL)));
+  sync_pb::EntitySpecifics entity_specifics;
+  sync_pb::TypedUrlSpecifics* typed_url = entity_specifics.mutable_typed_url();
+  WriteToTypedUrlSpecifics(server_row, server_visits, typed_url);
+  StartSyncing({*typed_url});
+
+  // Check that the backend was updated correctly.
+  VisitVector all_visits;
+  base::Time server_time = base::Time::FromInternalValue(6);
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+  ASSERT_EQ(2U, all_visits.size());
+  EXPECT_EQ(server_time, all_visits.back().visit_time);
+  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+      all_visits.back().transition, server_visits[0].transition));
+  URLRow url_row;
+  EXPECT_TRUE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  EXPECT_EQ(kTitle2, base::UTF16ToUTF8(url_row.title()));
+
+  // Check that the sync was updated correctly.
+  // The local history visit should not be added to sync because it is older
+  // than sync's oldest visit.
+  ASSERT_EQ(1U, processor().put_multimap().size());
+
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+  ASSERT_EQ(1, url_specifics.visits_size());
+  EXPECT_EQ(6, url_specifics.visits(0));
+  ASSERT_EQ(1, url_specifics.visit_transitions_size());
+  EXPECT_EQ(static_cast<const int>(visits[0].transition),
+            url_specifics.visit_transitions(0));
+}
+
+// Add a url to the local and sync data before sync begins, with the local data
+// having more recent visits. Check that starting sync updates the sync
+// with the local visits, while the older sync visit is not pushed to the
+// backend. Sync's title should be updated to the local version due to the more
+// recent timestamp.
+TEST_F(TypedURLSyncBridgeTest, MergeUrlOldSync) {
+  // Add a url to backend.
+  VisitVector visits;
+  URLRow local_row = MakeTypedUrlRow(kURL, kTitle2, 1, 3, false, &visits);
+  fake_history_backend_->SetVisitsForUrl(local_row, visits);
+
+  // Create sync data for the same url with an older visit.
+  VisitVector server_visits;
+  URLRow server_row =
+      MakeTypedUrlRow(kURL, kTitle, 1, 2, false, &server_visits);
+  sync_pb::EntitySpecifics entity_specifics;
+  sync_pb::TypedUrlSpecifics* typed_url = entity_specifics.mutable_typed_url();
+  WriteToTypedUrlSpecifics(server_row, server_visits, typed_url);
+  StartSyncing({*typed_url});
+
+  // Check that the backend was not updated.
+  VisitVector all_visits;
+  base::Time local_visit_time = base::Time::FromInternalValue(3);
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+  ASSERT_EQ(1U, all_visits.size());
+  EXPECT_EQ(local_visit_time, all_visits[0].visit_time);
+
+  // Check that the server was updated correctly.
+  // The local history visit should not be added to sync because it is older
+  // than sync's oldest visit.
+  ASSERT_EQ(1U, processor().put_multimap().size());
+
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+  ASSERT_EQ(1, url_specifics.visits_size());
+  EXPECT_EQ(3, url_specifics.visits(0));
+  EXPECT_EQ(kTitle2, url_specifics.title());
+  ASSERT_EQ(1, url_specifics.visit_transitions_size());
+  EXPECT_EQ(static_cast<const int>(visits[0].transition),
+            url_specifics.visit_transitions(0));
+}
+
+// Check that there is no crash during start sync, if history backend and sync
+// have same url, but sync has username/password in it.
+// Also check sync will not accept url with username and password.
+TEST_F(TypedURLSyncBridgeTest, MergeUrlsWithUsernameAndPassword) {
+  const char kURLWithUsernameAndPassword[] =
+      "http://username:password@pie.com/";
+
+  // Add a url to backend.
+  VisitVector visits;
+  URLRow local_row = MakeTypedUrlRow(kURL, kTitle2, 1, 3, false, &visits);
+  fake_history_backend_->SetVisitsForUrl(local_row, visits);
+
+  // Create sync data for the same url but contain username and password.
+  VisitVector server_visits;
+  URLRow server_row = MakeTypedUrlRow(kURLWithUsernameAndPassword, kTitle, 1, 3,
+                                      false, &server_visits);
+  sync_pb::EntitySpecifics entity_specifics;
+  sync_pb::TypedUrlSpecifics* typed_url = entity_specifics.mutable_typed_url();
+  WriteToTypedUrlSpecifics(server_row, server_visits, typed_url);
+
+  // Make sure there is no crash when merge two urls.
+  StartSyncing({*typed_url});
+
+  // Notify typed url sync service of the update.
+  bridge()->OnURLVisited(fake_history_backend_.get(), ui::PAGE_TRANSITION_TYPED,
+                         server_row, RedirectList(),
+                         base::Time::FromInternalValue(7));
+
+  // Check username/password url is not synced.
+  ASSERT_EQ(1U, processor().put_multimap().size());
+}
+
 // Starting sync with both local and sync have same typed URL, but different
 // visit. After merge, both local and sync should have two same visits.
 TEST_F(TypedURLSyncBridgeTest, SimpleMerge) {
@@ -406,4 +772,795 @@ TEST_F(TypedURLSyncBridgeTest, SimpleMerge) {
       all_visits[1].transition, visits2[0].transition));
 }
 
+// Create a local typed URL with one TYPED visit after sync has started. Check
+// that sync is sent an ADD change for the new URL.
+TEST_F(TypedURLSyncBridgeTest, AddLocalTypedUrl) {
+  // Create a local typed URL (simulate a typed visit) that is not already
+  // in sync. Check that sync is sent an ADD change for the existing URL.
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(1, 0, urls, &url_rows, &visit_vectors));
+
+  URLRow url_row = url_rows.front();
+  VisitVector visits = visit_vectors.front();
+
+  // Check change processor.
+  ASSERT_EQ(1U, processor().put_multimap().size());
+
+  // Get typed url specifics.
+  auto it = processor().put_multimap().begin();
+  sync_pb::TypedUrlSpecifics url_specifics = it->second->specifics.typed_url();
+
+  EXPECT_TRUE(URLsEqual(url_row, url_specifics));
+  ASSERT_EQ(1, url_specifics.visits_size());
+  ASSERT_EQ(static_cast<const int>(visits.size()), url_specifics.visits_size());
+  EXPECT_EQ(visits[0].visit_time.ToInternalValue(), url_specifics.visits(0));
+  EXPECT_EQ(static_cast<const int>(visits[0].transition),
+            url_specifics.visit_transitions(0));
+}
+
+// Update a local typed URL that is already synced. Check that sync is sent an
+// UPDATE for the existing url, but RELOAD visits aren't synced.
+TEST_F(TypedURLSyncBridgeTest, UpdateLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+
+  // Update the URL row, adding another typed visit to the visit vector.
+  URLRows changed_urls;
+  VisitVector visits;
+  URLRow url_row = MakeTypedUrlRow(kURL, kTitle, 1, 3, false, &visits);
+  AddNewestVisit(ui::PAGE_TRANSITION_TYPED, 7, &url_row, &visits);
+  AddNewestVisit(ui::PAGE_TRANSITION_RELOAD, 8, &url_row, &visits);
+  AddNewestVisit(ui::PAGE_TRANSITION_LINK, 9, &url_row, &visits);
+  fake_history_backend_->SetVisitsForUrl(url_row, visits);
+  changed_urls.push_back(url_row);
+
+  // Notify typed url sync service of the update.
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(0U, changes_multimap.size());
+  bridge()->OnURLsModified(fake_history_backend_.get(), changed_urls);
+  ASSERT_EQ(1U, changes_multimap.size());
+
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+  EXPECT_TRUE(URLsEqual(url_row, url_specifics));
+  ASSERT_EQ(3, url_specifics.visits_size());
+
+  // Check that each visit has been translated/communicated correctly.
+  // Note that the specifics record visits in chronological order, and the
+  // visits from the db are in reverse chronological order.
+  EXPECT_EQ(visits[0].visit_time.ToInternalValue(), url_specifics.visits(2));
+  EXPECT_EQ(static_cast<const int>(visits[0].transition),
+            url_specifics.visit_transitions(2));
+  EXPECT_EQ(visits[2].visit_time.ToInternalValue(), url_specifics.visits(1));
+  EXPECT_EQ(static_cast<const int>(visits[2].transition),
+            url_specifics.visit_transitions(1));
+  EXPECT_EQ(visits[3].visit_time.ToInternalValue(), url_specifics.visits(0));
+  EXPECT_EQ(static_cast<const int>(visits[3].transition),
+            url_specifics.visit_transitions(0));
+}
+
+// Append a RELOAD visit to a typed url that is already synced. Check that sync
+// does not receive any updates.
+TEST_F(TypedURLSyncBridgeTest, ReloadVisitLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(1, 0, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(1U, changes_multimap.size());
+
+  // Update the URL row, adding another typed visit to the visit vector.
+  URLRow url_row = url_rows.front();
+  URLRows changed_urls;
+  VisitVector new_visits;
+  AddNewestVisit(ui::PAGE_TRANSITION_RELOAD, 7, &url_row, &new_visits);
+  fake_history_backend_->SetVisitsForUrl(url_row, new_visits);
+  changed_urls.push_back(url_row);
+
+  // Notify typed url sync service of the update.
+  bridge()->OnURLVisited(fake_history_backend_.get(),
+                         ui::PAGE_TRANSITION_RELOAD, url_row, RedirectList(),
+                         base::Time::FromInternalValue(7));
+  // No change pass to processor
+  ASSERT_EQ(1U, changes_multimap.size());
+}
+
+// Appends a LINK visit to an existing typed url. Check that sync does not
+// receive any changes.
+TEST_F(TypedURLSyncBridgeTest, LinkVisitLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(1, 0, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(1U, changes_multimap.size());
+
+  // Update the URL row, adding a non-typed visit to the visit vector.
+  URLRow url_row = url_rows.front();
+  VisitVector new_visits;
+  AddNewestVisit(ui::PAGE_TRANSITION_LINK, 6, &url_row, &new_visits);
+  fake_history_backend_->SetVisitsForUrl(url_row, new_visits);
+
+  ui::PageTransition transition = ui::PAGE_TRANSITION_LINK;
+  // Notify typed url sync service of non-typed visit, expect no change.
+  bridge()->OnURLVisited(fake_history_backend_.get(), transition, url_row,
+                         RedirectList(), base::Time::FromInternalValue(6));
+  // No change pass to processor
+  ASSERT_EQ(1U, changes_multimap.size());
+}
+
+// Appends a series of LINK visits followed by a TYPED one to an existing typed
+// url. Check that sync receives an UPDATE with the newest visit data.
+TEST_F(TypedURLSyncBridgeTest, TypedVisitLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+
+  // Update the URL row, adding another typed visit to the visit vector.
+  VisitVector visits;
+  URLRow url_row = MakeTypedUrlRow(kURL, kTitle, 1, 3, false, &visits);
+  AddOldestVisit(ui::PAGE_TRANSITION_LINK, 1, &url_row, &visits);
+  AddNewestVisit(ui::PAGE_TRANSITION_LINK, 6, &url_row, &visits);
+  AddNewestVisit(ui::PAGE_TRANSITION_TYPED, 7, &url_row, &visits);
+  fake_history_backend_->SetVisitsForUrl(url_row, visits);
+
+  // Notify typed url sync service of typed visit.
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(0U, changes_multimap.size());
+  ui::PageTransition transition = ui::PAGE_TRANSITION_TYPED;
+  bridge()->OnURLVisited(fake_history_backend_.get(), transition, url_row,
+                         RedirectList(), base::Time::Now());
+
+  ASSERT_EQ(1U, changes_multimap.size());
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+
+  EXPECT_TRUE(URLsEqual(url_row, url_specifics));
+  EXPECT_EQ(4, url_specifics.visits_size());
+
+  // Check that each visit has been translated/communicated correctly.
+  // Note that the specifics record visits in chronological order, and the
+  // visits from the db are in reverse chronological order.
+  int r = url_specifics.visits_size() - 1;
+  for (int i = 0; i < url_specifics.visits_size(); ++i, --r) {
+    EXPECT_EQ(visits[i].visit_time.ToInternalValue(), url_specifics.visits(r));
+    EXPECT_EQ(static_cast<const int>(visits[i].transition),
+              url_specifics.visit_transitions(r));
+  }
+}
+
+// Delete several (but not all) local typed urls. Check that sync receives the
+// DELETE changes, and the non-deleted urls remain synced.
+TEST_F(TypedURLSyncBridgeTest, DeleteLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back("http://pie.com/");
+  urls.push_back("http://cake.com/");
+  urls.push_back("http://google.com/");
+  urls.push_back("http://foo.com/");
+  urls.push_back("http://bar.com/");
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(4, 1, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(4U, changes_multimap.size());
+
+  // Simulate visit expiry of typed visit, no syncing is done
+  // This is to test that sync relies on the in-memory cache to know
+  // which urls were typed and synced, and should be deleted.
+  url_rows[0].set_typed_count(0);
+  VisitVector visits;
+  fake_history_backend_->SetVisitsForUrl(url_rows[0], visits);
+
+  // Delete some urls from backend and create deleted row vector.
+  URLRows rows;
+  std::set<std::string> deleted_storage_keys;
+  for (size_t i = 0; i < 3u; ++i) {
+    std::string storage_key = GetStorageKey(url_rows[i].url().spec());
+    deleted_storage_keys.insert(storage_key);
+    fake_history_backend_->DeleteURL(url_rows[i].url());
+    rows.push_back(url_rows[i]);
+  }
+
+  // Notify typed url sync service.
+  bridge()->OnURLsDeleted(fake_history_backend_.get(), false, false, rows,
+                          std::set<GURL>());
+
+  const auto& delete_set = processor().delete_set();
+  ASSERT_EQ(3U, delete_set.size());
+  for (const std::string& storage_key : delete_set) {
+    EXPECT_TRUE(deleted_storage_keys.find(storage_key) !=
+                deleted_storage_keys.end());
+    deleted_storage_keys.erase(storage_key);
+  }
+  ASSERT_TRUE(deleted_storage_keys.empty());
+}
+
+// Saturate the visits for a typed url with both TYPED and LINK navigations.
+// Check that no more than kMaxTypedURLVisits are synced, and that LINK visits
+// are dropped rather than TYPED ones.
+TEST_F(TypedURLSyncBridgeTest, MaxVisitLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(0, 1, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(0U, changes_multimap.size());
+
+  URLRow url_row = url_rows.front();
+  VisitVector visits;
+
+  // Add |kMaxTypedUrlVisits| + 10 visits to the url. The 10 oldest
+  // non-typed visits are expected to be skipped.
+  int i = 1;
+  for (; i <= kMaxTypedUrlVisits - 20; ++i)
+    AddNewestVisit(ui::PAGE_TRANSITION_TYPED, i, &url_row, &visits);
+  for (; i <= kMaxTypedUrlVisits; ++i)
+    AddNewestVisit(ui::PAGE_TRANSITION_LINK, i, &url_row, &visits);
+  for (; i <= kMaxTypedUrlVisits + 10; ++i)
+    AddNewestVisit(ui::PAGE_TRANSITION_TYPED, i, &url_row, &visits);
+
+  fake_history_backend_->SetVisitsForUrl(url_row, visits);
+
+  // Notify typed url sync service of typed visit.
+  ui::PageTransition transition = ui::PAGE_TRANSITION_TYPED;
+  bridge()->OnURLVisited(fake_history_backend_.get(), transition, url_row,
+                         RedirectList(), base::Time::Now());
+
+  ASSERT_EQ(1U, changes_multimap.size());
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+  ASSERT_EQ(kMaxTypedUrlVisits, url_specifics.visits_size());
+
+  // Check that each visit has been translated/communicated correctly.
+  // Note that the specifics records visits in chronological order, and the
+  // visits from the db are in reverse chronological order.
+  int num_typed_visits_synced = 0;
+  int num_other_visits_synced = 0;
+  int r = url_specifics.visits_size() - 1;
+  for (int i = 0; i < url_specifics.visits_size(); ++i, --r) {
+    if (url_specifics.visit_transitions(i) ==
+        static_cast<int32_t>(ui::PAGE_TRANSITION_TYPED)) {
+      ++num_typed_visits_synced;
+    } else {
+      ++num_other_visits_synced;
+    }
+  }
+  EXPECT_EQ(kMaxTypedUrlVisits - 10, num_typed_visits_synced);
+  EXPECT_EQ(10, num_other_visits_synced);
+}
+
+// Add enough visits to trigger throttling of updates to a typed url. Check that
+// sync does not receive an update until the proper throttle interval has been
+// reached.
+TEST_F(TypedURLSyncBridgeTest, ThrottleVisitLocalTypedUrl) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(0, 1, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(0U, changes_multimap.size());
+
+  URLRow url_row = url_rows.front();
+  VisitVector visits;
+
+  // Add enough visits to the url so that typed count is above the throttle
+  // limit, and not right on the interval that gets synced.
+  int i = 1;
+  for (; i < kVisitThrottleThreshold + kVisitThrottleMultiple / 2; ++i)
+    AddNewestVisit(ui::PAGE_TRANSITION_TYPED, i, &url_row, &visits);
+  fake_history_backend_->SetVisitsForUrl(url_row, visits);
+
+  // Notify typed url sync service of typed visit.
+  ui::PageTransition transition = ui::PAGE_TRANSITION_TYPED;
+  bridge()->OnURLVisited(fake_history_backend_.get(), transition, url_row,
+                         RedirectList(), base::Time::Now());
+
+  // Should throttle, so sync and local cache should not update.
+  ASSERT_EQ(0U, changes_multimap.size());
+
+  visits.clear();
+  for (; i % kVisitThrottleMultiple != 1; ++i)
+    AddNewestVisit(ui::PAGE_TRANSITION_TYPED, i, &url_row, &visits);
+  --i;  // Account for the increment before the condition ends.
+  fake_history_backend_->SetVisitsForUrl(url_row, visits);
+
+  // Notify typed url sync service of typed visit.
+  bridge()->OnURLVisited(fake_history_backend_.get(), transition, url_row,
+                         RedirectList(), base::Time::Now());
+
+  ASSERT_EQ(1U, changes_multimap.size());
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+  ASSERT_EQ(i, url_specifics.visits_size());
+}
+
+// Create a remote typed URL and visit, then send to sync bridge after sync
+// has started. Check that local DB is received the new URL and visit.
+TEST_F(TypedURLSyncBridgeTest, AddUrlAndVisits) {
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  VisitVector visits = ApplyUrlAndVisitsChange(kURL, kTitle, 1, 3, false,
+                                               EntityChange::ACTION_ADD);
+
+  ASSERT_EQ(0U, processor().put_multimap().size());
+  ASSERT_EQ(1U, processor().update_multimap().size());
+  ASSERT_EQ(0U, processor().untrack_set().size());
+
+  // Verify processor receive correct upate storage key.
+  const auto& it = processor().update_multimap().begin();
+  EXPECT_EQ(it->first, IntToStroageKey(1));
+  EXPECT_TRUE(it->second->specifics.has_typed_url());
+  EXPECT_EQ(it->second->specifics.typed_url().url(), kURL);
+  EXPECT_EQ(it->second->specifics.typed_url().title(), kTitle);
+
+  base::Time visit_time = base::Time::FromInternalValue(3);
+  VisitVector all_visits;
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+  EXPECT_EQ(1U, all_visits.size());
+  EXPECT_EQ(visit_time, all_visits[0].visit_time);
+  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+      all_visits[0].transition, visits[0].transition));
+  URLRow url_row;
+  EXPECT_TRUE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  EXPECT_EQ(kTitle, base::UTF16ToUTF8(url_row.title()));
+}
+
+// Create a remote typed URL with expired visit, then send to sync bridge after
+// sync has started. Check that local DB did not receive the expired URL and
+// visit.
+TEST_F(TypedURLSyncBridgeTest, AddExpiredUrlAndVisits) {
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  VisitVector visits = ApplyUrlAndVisitsChange(kURL, kTitle, 1, kExpiredVisit,
+                                               false, EntityChange::ACTION_ADD);
+
+  ASSERT_EQ(0U, processor().put_multimap().size());
+  ASSERT_EQ(0U, processor().update_multimap().size());
+  ASSERT_EQ(1U, processor().untrack_set().size());
+
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_EQ(0, url_id);
+}
+
+// Update a remote typed URL and create a new visit that is already synced, then
+// send the update to sync bridge. Check that local DB is received an
+// UPDATE for the existing url and new visit.
+TEST_F(TypedURLSyncBridgeTest, UpdateUrlAndVisits) {
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+
+  VisitVector visits = ApplyUrlAndVisitsChange(kURL, kTitle, 1, 3, false,
+                                               EntityChange::ACTION_ADD);
+  base::Time visit_time = base::Time::FromInternalValue(3);
+  VisitVector all_visits;
+  URLRow url_row;
+
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+
+  EXPECT_EQ(1U, all_visits.size());
+  EXPECT_EQ(visit_time, all_visits[0].visit_time);
+  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+      all_visits[0].transition, visits[0].transition));
+  EXPECT_TRUE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  EXPECT_EQ(kTitle, base::UTF16ToUTF8(url_row.title()));
+
+  VisitVector new_visits = ApplyUrlAndVisitsChange(kURL, kTitle2, 2, 6, false,
+                                                   EntityChange::ACTION_UPDATE);
+
+  base::Time new_visit_time = base::Time::FromInternalValue(6);
+  url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+
+  EXPECT_EQ(2U, all_visits.size());
+  EXPECT_EQ(new_visit_time, all_visits.back().visit_time);
+  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+      all_visits.back().transition, new_visits[0].transition));
+  EXPECT_TRUE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  EXPECT_EQ(kTitle2, base::UTF16ToUTF8(url_row.title()));
+}
+
+// Delete a typed urls which already synced. Check that local DB receives the
+// DELETE changes.
+TEST_F(TypedURLSyncBridgeTest, DeleteUrlAndVisits) {
+  URLRows url_rows;
+  std::vector<VisitVector> visit_vectors;
+  std::vector<std::string> urls;
+  urls.push_back(kURL);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+  ASSERT_TRUE(BuildAndPushLocalChanges(1, 0, urls, &url_rows, &visit_vectors));
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(1U, changes_multimap.size());
+
+  base::Time visit_time = base::Time::FromInternalValue(3);
+  VisitVector all_visits;
+  URLID url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_NE(0, url_id);
+  fake_history_backend_->GetVisitsForURL(url_id, &all_visits);
+  EXPECT_EQ(1U, all_visits.size());
+  EXPECT_EQ(visit_time, all_visits[0].visit_time);
+  EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+      all_visits[0].transition, visit_vectors[0][0].transition));
+  URLRow url_row;
+  EXPECT_TRUE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  EXPECT_EQ(kTitle, base::UTF16ToUTF8(url_row.title()));
+
+  // Add observer back to check if TypedUrlSyncBridge receive delete
+  // changes back from fake_history_backend_.
+  AddObserver();
+
+  ApplyUrlAndVisitsChange(kURL, kTitle, 1, 3, false,
+                          EntityChange::ACTION_DELETE);
+
+  EXPECT_FALSE(fake_history_backend_->GetURL(GURL(kURL), &url_row));
+  url_id = fake_history_backend_->GetIdByUrl(GURL(kURL));
+  ASSERT_EQ(0, url_id);
+
+  // Check TypedUrlSyncBridge did not receive update since the update is
+  // trigered by it.
+  ASSERT_EQ(1U, changes_multimap.size());
+}
+
+// Create two set of visits for history DB and sync DB, two same set of visits
+// are same. Check DiffVisits will return empty set of diff visits.
+TEST_F(TypedURLSyncBridgeTest, DiffVisitsSame) {
+  VisitVector old_visits;
+  sync_pb::TypedUrlSpecifics new_url;
+
+  const int64_t visits[] = {1024, 2065, 65534, 1237684};
+
+  for (int64_t visit : visits) {
+    old_visits.push_back(VisitRow(0, base::Time::FromInternalValue(visit), 0,
+                                  ui::PAGE_TRANSITION_TYPED, 0));
+    new_url.add_visits(visit);
+    new_url.add_visit_transitions(ui::PAGE_TRANSITION_TYPED);
+  }
+
+  std::vector<VisitInfo> new_visits;
+  VisitVector removed_visits;
+
+  DiffVisits(old_visits, new_url, &new_visits, &removed_visits);
+  EXPECT_TRUE(new_visits.empty());
+  EXPECT_TRUE(removed_visits.empty());
+}
+
+// Create two set of visits for history DB and sync DB. Check DiffVisits will
+// return correct set of diff visits.
+TEST_F(TypedURLSyncBridgeTest, DiffVisitsRemove) {
+  VisitVector old_visits;
+  sync_pb::TypedUrlSpecifics new_url;
+
+  const int64_t visits_left[] = {1,    2,     1024,    1500,   2065,
+                                 6000, 65534, 1237684, 2237684};
+  const int64_t visits_right[] = {1024, 2065, 65534, 1237684};
+
+  // DiffVisits will not remove the first visit, because we never delete visits
+  // from the start of the array (since those visits can get truncated by the
+  // size-limiting code).
+  const int64_t visits_removed[] = {1500, 6000, 2237684};
+
+  for (int64_t visit : visits_left) {
+    old_visits.push_back(VisitRow(0, base::Time::FromInternalValue(visit), 0,
+                                  ui::PAGE_TRANSITION_TYPED, 0));
+  }
+
+  for (int64_t visit : visits_right) {
+    new_url.add_visits(visit);
+    new_url.add_visit_transitions(ui::PAGE_TRANSITION_TYPED);
+  }
+
+  std::vector<VisitInfo> new_visits;
+  VisitVector removed_visits;
+
+  DiffVisits(old_visits, new_url, &new_visits, &removed_visits);
+  EXPECT_TRUE(new_visits.empty());
+  ASSERT_EQ(removed_visits.size(), arraysize(visits_removed));
+  for (size_t i = 0; i < arraysize(visits_removed); ++i) {
+    EXPECT_EQ(removed_visits[i].visit_time.ToInternalValue(),
+              visits_removed[i]);
+  }
+}
+
+// Create two set of visits for history DB and sync DB. Check DiffVisits will
+// return correct set of diff visits.
+TEST_F(TypedURLSyncBridgeTest, DiffVisitsAdd) {
+  VisitVector old_visits;
+  sync_pb::TypedUrlSpecifics new_url;
+
+  const int64_t visits_left[] = {1024, 2065, 65534, 1237684};
+  const int64_t visits_right[] = {1,    1024,  1500,    2065,
+                                  6000, 65534, 1237684, 2237684};
+
+  const int64_t visits_added[] = {1, 1500, 6000, 2237684};
+
+  for (int64_t visit : visits_left) {
+    old_visits.push_back(VisitRow(0, base::Time::FromInternalValue(visit), 0,
+                                  ui::PAGE_TRANSITION_TYPED, 0));
+  }
+
+  for (int64_t visit : visits_right) {
+    new_url.add_visits(visit);
+    new_url.add_visit_transitions(ui::PAGE_TRANSITION_TYPED);
+  }
+
+  std::vector<VisitInfo> new_visits;
+  VisitVector removed_visits;
+
+  DiffVisits(old_visits, new_url, &new_visits, &removed_visits);
+  EXPECT_TRUE(removed_visits.empty());
+  ASSERT_TRUE(new_visits.size() == arraysize(visits_added));
+  for (size_t i = 0; i < arraysize(visits_added); ++i) {
+    EXPECT_EQ(new_visits[i].first.ToInternalValue(), visits_added[i]);
+    EXPECT_TRUE(ui::PageTransitionTypeIncludingQualifiersIs(
+        new_visits[i].second, ui::PAGE_TRANSITION_TYPED));
+  }
+}
+
+// Create three visits, check RELOAD visit is removed by
+// WriteToTypedUrlSpecifics so it won't apply to sync DB.
+TEST_F(TypedURLSyncBridgeTest, WriteTypedUrlSpecifics) {
+  VisitVector visits;
+  visits.push_back(CreateVisit(ui::PAGE_TRANSITION_TYPED, 1));
+  visits.push_back(CreateVisit(ui::PAGE_TRANSITION_RELOAD, 2));
+  visits.push_back(CreateVisit(ui::PAGE_TRANSITION_LINK, 3));
+
+  URLRow url(MakeTypedUrlRow(kURL, kTitle, 0, 100, false, &visits));
+  sync_pb::TypedUrlSpecifics typed_url;
+  WriteToTypedUrlSpecifics(url, visits, &typed_url);
+  // RELOAD visits should be removed.
+  EXPECT_EQ(2, typed_url.visits_size());
+  EXPECT_EQ(typed_url.visit_transitions_size(), typed_url.visits_size());
+  EXPECT_EQ(1, typed_url.visits(0));
+  EXPECT_EQ(3, typed_url.visits(1));
+  EXPECT_EQ(static_cast<int32_t>(ui::PAGE_TRANSITION_TYPED),
+            typed_url.visit_transitions(0));
+  EXPECT_EQ(static_cast<int32_t>(ui::PAGE_TRANSITION_LINK),
+            typed_url.visit_transitions(1));
+}
+
+// Create 101 visits, check WriteToTypedUrlSpecifics will only keep 100 visits.
+TEST_F(TypedURLSyncBridgeTest, TooManyVisits) {
+  VisitVector visits;
+  int64_t timestamp = 1000;
+  visits.push_back(CreateVisit(ui::PAGE_TRANSITION_TYPED, timestamp++));
+  for (int i = 0; i < 100; ++i) {
+    visits.push_back(CreateVisit(ui::PAGE_TRANSITION_LINK, timestamp++));
+  }
+  URLRow url(MakeTypedUrlRow(kURL, kTitle, 0, timestamp++, false, &visits));
+  sync_pb::TypedUrlSpecifics typed_url;
+  WriteToTypedUrlSpecifics(url, visits, &typed_url);
+  // # visits should be capped at 100.
+  EXPECT_EQ(100, typed_url.visits_size());
+  EXPECT_EQ(typed_url.visit_transitions_size(), typed_url.visits_size());
+  EXPECT_EQ(1000, typed_url.visits(0));
+  // Visit with timestamp of 1001 should be omitted since we should have
+  // skipped that visit to stay under the cap.
+  EXPECT_EQ(1002, typed_url.visits(1));
+  EXPECT_EQ(static_cast<int32_t>(ui::PAGE_TRANSITION_TYPED),
+            typed_url.visit_transitions(0));
+  EXPECT_EQ(static_cast<int32_t>(ui::PAGE_TRANSITION_LINK),
+            typed_url.visit_transitions(1));
+}
+
+// Create 306 visits, check WriteToTypedUrlSpecifics will only keep 100 typed
+// visits.
+TEST_F(TypedURLSyncBridgeTest, TooManyTypedVisits) {
+  VisitVector visits;
+  int64_t timestamp = 1000;
+  for (int i = 0; i < 102; ++i) {
+    visits.push_back(CreateVisit(ui::PAGE_TRANSITION_TYPED, timestamp++));
+    visits.push_back(CreateVisit(ui::PAGE_TRANSITION_LINK, timestamp++));
+    visits.push_back(CreateVisit(ui::PAGE_TRANSITION_RELOAD, timestamp++));
+  }
+  URLRow url(MakeTypedUrlRow(kURL, kTitle, 0, timestamp++, false, &visits));
+  sync_pb::TypedUrlSpecifics typed_url;
+  WriteToTypedUrlSpecifics(url, visits, &typed_url);
+  // # visits should be capped at 100.
+  EXPECT_EQ(100, typed_url.visits_size());
+  EXPECT_EQ(typed_url.visit_transitions_size(), typed_url.visits_size());
+  // First two typed visits should be skipped.
+  EXPECT_EQ(1006, typed_url.visits(0));
+
+  // Ensure there are no non-typed visits since that's all that should fit.
+  for (int i = 0; i < typed_url.visits_size(); ++i) {
+    EXPECT_EQ(static_cast<int32_t>(ui::PAGE_TRANSITION_TYPED),
+              typed_url.visit_transitions(i));
+  }
+}
+
+// Create a typed url without visit, check WriteToTypedUrlSpecifics will return
+// false for it.
+TEST_F(TypedURLSyncBridgeTest, NoTypedVisits) {
+  VisitVector visits;
+  URLRow url(MakeTypedUrlRow(kURL, kTitle, 0, 1000, false, &visits));
+  sync_pb::TypedUrlSpecifics typed_url;
+  EXPECT_FALSE(WriteToTypedUrlSpecifics(url, visits, &typed_url));
+  // URLs with no typed URL visits should not been written to specifics.
+  EXPECT_EQ(0, typed_url.visits_size());
+}
+
+TEST_F(TypedURLSyncBridgeTest, MergeUrls) {
+  VisitVector visits1;
+  URLRow row1(MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &visits1));
+  sync_pb::TypedUrlSpecifics specs1(
+      MakeTypedUrlSpecifics(kURL, kTitle, 3, false));
+  URLRow new_row1((GURL(kURL)));
+  std::vector<VisitInfo> new_visits1;
+  EXPECT_TRUE(TypedURLSyncBridgeTest::MergeUrls(specs1, row1, &visits1,
+                                                &new_row1, &new_visits1) ==
+              TypedURLSyncBridgeTest::DIFF_NONE);
+
+  VisitVector visits2;
+  URLRow row2(MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &visits2));
+  sync_pb::TypedUrlSpecifics specs2(
+      MakeTypedUrlSpecifics(kURL, kTitle, 3, true));
+  VisitVector expected_visits2;
+  URLRow expected2(
+      MakeTypedUrlRow(kURL, kTitle, 2, 3, true, &expected_visits2));
+  URLRow new_row2((GURL(kURL)));
+  std::vector<VisitInfo> new_visits2;
+  EXPECT_TRUE(TypedURLSyncBridgeTest::MergeUrls(specs2, row2, &visits2,
+                                                &new_row2, &new_visits2) ==
+              TypedURLSyncBridgeTest::DIFF_LOCAL_ROW_CHANGED);
+  EXPECT_TRUE(URLsEqual(new_row2, expected2));
+
+  VisitVector visits3;
+  URLRow row3(MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &visits3));
+  sync_pb::TypedUrlSpecifics specs3(
+      MakeTypedUrlSpecifics(kURL, kTitle2, 3, true));
+  VisitVector expected_visits3;
+  URLRow expected3(
+      MakeTypedUrlRow(kURL, kTitle2, 2, 3, true, &expected_visits3));
+  URLRow new_row3((GURL(kURL)));
+  std::vector<VisitInfo> new_visits3;
+  EXPECT_EQ(TypedURLSyncBridgeTest::DIFF_LOCAL_ROW_CHANGED |
+                TypedURLSyncBridgeTest::DIFF_NONE,
+            TypedURLSyncBridgeTest::MergeUrls(specs3, row3, &visits3, &new_row3,
+                                              &new_visits3));
+  EXPECT_TRUE(URLsEqual(new_row3, expected3));
+
+  // Create one node in history DB with timestamp of 3, and one node in sync
+  // DB with timestamp of 4. Result should contain one new item (4).
+  VisitVector visits4;
+  URLRow row4(MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &visits4));
+  sync_pb::TypedUrlSpecifics specs4(
+      MakeTypedUrlSpecifics(kURL, kTitle2, 4, false));
+  VisitVector expected_visits4;
+  URLRow expected4(
+      MakeTypedUrlRow(kURL, kTitle2, 2, 4, false, &expected_visits4));
+  URLRow new_row4((GURL(kURL)));
+  std::vector<VisitInfo> new_visits4;
+  EXPECT_EQ(TypedURLSyncBridgeTest::DIFF_UPDATE_NODE |
+                TypedURLSyncBridgeTest::DIFF_LOCAL_ROW_CHANGED |
+                TypedURLSyncBridgeTest::DIFF_LOCAL_VISITS_ADDED,
+            TypedURLSyncBridgeTest::MergeUrls(specs4, row4, &visits4, &new_row4,
+                                              &new_visits4));
+  EXPECT_EQ(1U, new_visits4.size());
+  EXPECT_EQ(specs4.visits(0), new_visits4[0].first.ToInternalValue());
+  EXPECT_TRUE(URLsEqual(new_row4, expected4));
+  EXPECT_EQ(2U, visits4.size());
+
+  VisitVector visits5;
+  URLRow row5(MakeTypedUrlRow(kURL, kTitle, 1, 4, false, &visits5));
+  sync_pb::TypedUrlSpecifics specs5(
+      MakeTypedUrlSpecifics(kURL, kTitle, 3, false));
+  VisitVector expected_visits5;
+  URLRow expected5(
+      MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &expected_visits5));
+  URLRow new_row5((GURL(kURL)));
+  std::vector<VisitInfo> new_visits5;
+
+  // UPDATE_NODE should be set because row5 has a newer last_visit timestamp.
+  EXPECT_EQ(TypedURLSyncBridgeTest::DIFF_UPDATE_NODE |
+                TypedURLSyncBridgeTest::DIFF_NONE,
+            TypedURLSyncBridgeTest::MergeUrls(specs5, row5, &visits5, &new_row5,
+                                              &new_visits5));
+  EXPECT_TRUE(URLsEqual(new_row5, expected5));
+  EXPECT_EQ(0U, new_visits5.size());
+}
+
+// Tests to ensure that we don't resurrect expired URLs (URLs that have been
+// deleted from the history DB but still exist in the sync DB).
+TEST_F(TypedURLSyncBridgeTest, MergeUrlsAfterExpiration) {
+  // First, create a history row that has two visits, with timestamps 2 and 3.
+  VisitVector(history_visits);
+  history_visits.push_back(VisitRow(0, base::Time::FromInternalValue(2), 0,
+                                    ui::PAGE_TRANSITION_TYPED, 0));
+  URLRow history_url(
+      MakeTypedUrlRow(kURL, kTitle, 2, 3, false, &history_visits));
+
+  // Now, create a sync node with visits at timestamps 1, 2, 3, 4.
+  sync_pb::TypedUrlSpecifics node(
+      MakeTypedUrlSpecifics(kURL, kTitle, 1, false));
+  node.add_visits(2);
+  node.add_visits(3);
+  node.add_visits(4);
+  node.add_visit_transitions(2);
+  node.add_visit_transitions(3);
+  node.add_visit_transitions(4);
+  URLRow new_history_url(history_url.url());
+  std::vector<VisitInfo> new_visits;
+  EXPECT_EQ(
+      TypedURLSyncBridgeTest::DIFF_NONE |
+          TypedURLSyncBridgeTest::DIFF_LOCAL_VISITS_ADDED,
+      TypedURLSyncBridgeTest::MergeUrls(node, history_url, &history_visits,
+                                        &new_history_url, &new_visits));
+  EXPECT_TRUE(URLsEqual(history_url, new_history_url));
+  EXPECT_EQ(1U, new_visits.size());
+  EXPECT_EQ(4U, new_visits[0].first.ToInternalValue());
+  // We should not sync the visit with timestamp #1 since it is earlier than
+  // any other visit for this URL in the history DB. But we should sync visit
+  // #4.
+  EXPECT_EQ(3U, history_visits.size());
+  EXPECT_EQ(2U, history_visits[0].visit_time.ToInternalValue());
+  EXPECT_EQ(3U, history_visits[1].visit_time.ToInternalValue());
+  EXPECT_EQ(4U, history_visits[2].visit_time.ToInternalValue());
+}
+
+// Create a local typed URL with one expired TYPED visit,
+// MergeSyncData should not pass it to sync. And then add a non
+// expired visit, OnURLsModified should only send the non expired visit to sync.
+TEST_F(TypedURLSyncBridgeTest, LocalExpiredTypedUrlDoNotSync) {
+  URLRow row;
+  URLRows changed_urls;
+  VisitVector visits;
+
+  // Add an expired typed URL to local.
+  row = MakeTypedUrlRow(kURL, kTitle, 1, kExpiredVisit, false, &visits);
+  fake_history_backend_->SetVisitsForUrl(row, visits);
+
+  StartSyncing(std::vector<TypedUrlSpecifics>());
+
+  // Check change processor did not receive expired typed URL.
+  const auto& changes_multimap = processor().put_multimap();
+  ASSERT_EQ(0U, changes_multimap.size());
+
+  // Add a non expired typed URL to local.
+  row = MakeTypedUrlRow(kURL, kTitle, 2, 1, false, &visits);
+  fake_history_backend_->SetVisitsForUrl(row, visits);
+
+  changed_urls.push_back(row);
+  // Notify typed url sync service of the update.
+  bridge()->OnURLsModified(fake_history_backend_.get(), changed_urls);
+
+  // Check change processor did not receive expired typed URL.
+  ASSERT_EQ(1U, changes_multimap.size());
+
+  // Get typed url specifics. Verify only a non-expired visit received.
+  sync_pb::TypedUrlSpecifics url_specifics = GetLastUpdateForURL(kURL);
+
+  EXPECT_TRUE(URLsEqual(row, url_specifics));
+  ASSERT_EQ(1, url_specifics.visits_size());
+  ASSERT_EQ(static_cast<const int>(visits.size() - 1),
+            url_specifics.visits_size());
+  EXPECT_EQ(visits[1].visit_time.ToInternalValue(), url_specifics.visits(0));
+  EXPECT_EQ(static_cast<const int>(visits[1].transition),
+            url_specifics.visit_transitions(0));
+}
+
 }  // namespace history