Sync user's custom spellcheck dictionary

chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc

Index: chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc
diff --git a/chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc b/chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc
index c890afcaa654000c8bbbc5d2976d013fce33c5bf..9bc09ba2cce32c8b8764a33f0e66a32b19d8b17f 100644
--- a/chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc
+++ b/chrome/browser/spellchecker/spellcheck_custom_dictionary_unittest.cc
@@ -5,6 +5,7 @@
 #include <vector>
 
 #include "base/file_util.h"
+#include "base/string_number_conversions.h"
 #include "chrome/browser/spellchecker/spellcheck_custom_dictionary.h"
 #include "chrome/browser/spellchecker/spellcheck_factory.h"
 #include "chrome/browser/spellchecker/spellcheck_service.h"
@@ -12,12 +13,38 @@
 #include "chrome/common/spellcheck_common.h"
 #include "chrome/test/base/testing_profile.h"
 #include "content/public/test/test_browser_thread.h"
+#include "sync/api/sync_change.h"
+#include "sync/api/sync_data.h"
+#include "sync/api/sync_error_factory.h"
+#include "sync/api/sync_error_factory_mock.h"
+#include "sync/protocol/sync.pb.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using content::BrowserThread;
 using chrome::spellcheck_common::WordList;
 
+namespace {
+
+// Get all sync data for the custom dictionary without limiting to maximum
+// number of syncable words.
+syncer::SyncDataList GetAllSyncDataNoLimit(
+    const SpellcheckCustomDictionary* dictionary) {
+  syncer::SyncDataList data;
+  std::string word;
+  for (WordList::const_iterator it = dictionary->GetWords().begin();
+       it != dictionary->GetWords().end();
+       ++it) {
+    word = *it;
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    data.push_back(syncer::SyncData::CreateLocalData(word, word, specifics));
+  }
+  return data;
+}
+
+}  // namespace
+
 static ProfileKeyedService* BuildSpellcheckService(Profile* profile) {
   return new SpellcheckService(profile);
 }
@@ -27,7 +54,7 @@ class SpellcheckCustomDictionaryTest : public testing::Test {
   SpellcheckCustomDictionaryTest()
       : ui_thread_(BrowserThread::UI, &message_loop_),
         file_thread_(BrowserThread::FILE, &message_loop_),
-        profile_(new TestingProfile()) {
+        profile_(new TestingProfile) {
   }
 
   void SetUp() OVERRIDE {
@@ -40,6 +67,39 @@ class SpellcheckCustomDictionaryTest : public testing::Test {
     MessageLoop::current()->RunUntilIdle();
   }
 
+  // A wrapper around SpellcheckCustomDictionary::LoadDictionaryFile private
+  // function to avoid a large number of FRIEND_TEST declarations in
+  // SpellcheckCustomDictionary.
+  chrome::spellcheck_common::WordList LoadDictionaryFile(const FilePath& path) {
+    return SpellcheckCustomDictionary::LoadDictionaryFile(path);
+  }
+
+  // A wrapper around SpellcheckCustomDictionary::UpdateDictionaryFile private
+  // function to avoid a large number of FRIEND_TEST declarations in
+  // SpellcheckCustomDictionary.
+  void UpdateDictionaryFile(
+      const SpellcheckCustomDictionary::Change& dictionary_change,
+      const FilePath& path) {
+    SpellcheckCustomDictionary::UpdateDictionaryFile(dictionary_change, path);
+  }
+
+  // A wrapper around SpellcheckCustomDictionary::OnLoaded private method to
+  // avoid a large number of FRIEND_TEST declarations in
+  // SpellcheckCustomDictionary.
+  void OnLoaded(
+      SpellcheckCustomDictionary& dictionary,
+      const chrome::spellcheck_common::WordList& custom_words) {
+    dictionary.OnLoaded(custom_words);
+  }
+
+  // A wrapper around SpellcheckCustomDictionary::Apply private method to avoid
+  // a large number of FRIEND_TEST declarations in SpellcheckCustomDictionary.
+  void Apply(
+      SpellcheckCustomDictionary& dictionary,
+      const SpellcheckCustomDictionary::Change& change) {
+    return dictionary.Apply(change);
+  }
+
   MessageLoop message_loop_;
   content::TestBrowserThread ui_thread_;
   content::TestBrowserThread file_thread_;
@@ -47,79 +107,96 @@ class SpellcheckCustomDictionaryTest : public testing::Test {
   scoped_ptr<TestingProfile> profile_;
 };
 
-TEST_F(SpellcheckCustomDictionaryTest, SpellcheckSetCustomWordList) {
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
+// A wrapper around SpellcheckCustomDictionary that does not own the wrapped
+// object. An instance of this class can be inside of a scoped pointer safely
+// while the dictionary is managed by another scoped pointer.
+class SyncChangeProcessorDelegate : public syncer::SyncChangeProcessor {
+ public:
+  explicit SyncChangeProcessorDelegate(SpellcheckCustomDictionary* dictionary)
+      : dictionary_(dictionary) {}
+  virtual ~SyncChangeProcessorDelegate() {}
 
-  WordList loaded_custom_words;
-  loaded_custom_words.push_back("foo");
-  loaded_custom_words.push_back("bar");
-  WordList expected(loaded_custom_words);
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  custom_dictionary->SetCustomWordList(&loaded_custom_words);
-  EXPECT_EQ(custom_dictionary->GetWords(), expected);
-}
+  // Overridden from syncer::SyncChangeProcessor:
+  virtual syncer::SyncError ProcessSyncChanges(
+      const tracked_objects::Location& from_here,
+      const syncer::SyncChangeList& change_list) OVERRIDE {
+    return dictionary_->ProcessSyncChanges(from_here, change_list);
+  }
 
-TEST_F(SpellcheckCustomDictionaryTest, CustomWordAddedAndRemovedLocally) {
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
+ private:
+  SpellcheckCustomDictionary* dictionary_;
+  DISALLOW_COPY_AND_ASSIGN(SyncChangeProcessorDelegate);
+};
 
-  WordList loaded_custom_words;
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  WordList expected;
-  EXPECT_EQ(custom_dictionary->GetWords(), expected);
-  custom_dictionary->CustomWordAddedLocally("foo");
-  expected.push_back("foo");
-  EXPECT_EQ(custom_dictionary->GetWords(), expected);
-  custom_dictionary->CustomWordAddedLocally("bar");
-  expected.push_back("bar");
-  EXPECT_EQ(custom_dictionary->GetWords(), expected);
+// An implementation of SyncErrorFactory that does not upload the error message
+// and updates an outside error counter. This lets us know the number of error
+// messages in an instance of this class after that instance is deleted.
+class SyncErrorFactoryStub : public syncer::SyncErrorFactory {
+ public:
+  explicit SyncErrorFactoryStub(int* error_counter)
+      : error_counter_(error_counter) {}
+  virtual ~SyncErrorFactoryStub() {}
 
-  custom_dictionary->CustomWordRemovedLocally("foo");
-  custom_dictionary->CustomWordRemovedLocally("bar");
-  expected.clear();
-  EXPECT_EQ(custom_dictionary->GetWords(), expected);
-}
+  // Overridden from syncer::SyncErrorFactory:
+  virtual syncer::SyncError CreateAndUploadError(
+      const tracked_objects::Location& location,
+      const std::string& message) OVERRIDE {
+    (*error_counter_)++;
+    return syncer::SyncError(location, message, syncer::DICTIONARY);
+  }
 
-TEST_F(SpellcheckCustomDictionaryTest, SaveAndLoad) {
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
+ private:
+  int* error_counter_;
+  DISALLOW_COPY_AND_ASSIGN(SyncErrorFactoryStub);
+};
+
+// Counts the number of notifications for dictionary load and change.
+class DictionaryObserverCounter : public SpellcheckCustomDictionary::Observer {
+ public:
+  DictionaryObserverCounter() : loads_(0), changes_(0) {}
+  virtual ~DictionaryObserverCounter() {}
+
+  int loads() const { return loads_; }
+  int changes() const { return changes_; }
+
+  // Overridden from SpellcheckCustomDictionary::Observer:
+  virtual void OnCustomDictionaryLoaded() OVERRIDE { loads_++; }
+  virtual void OnCustomDictionaryChanged(
+      const SpellcheckCustomDictionary::Change& change) OVERRIDE { changes_++; }
 
-  WordList loaded_custom_words;
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+ private:
+  int loads_;
+  int changes_;
+  DISALLOW_COPY_AND_ASSIGN(DictionaryObserverCounter);
+};
+
+TEST_F(SpellcheckCustomDictionaryTest, SaveAndLoad) {
+  FilePath path = profile_->GetPath().Append(chrome::kCustomDictionaryFileName);
+  WordList loaded_custom_words = LoadDictionaryFile(path);
 
   // The custom word list should be empty now.
   WordList expected;
-  EXPECT_EQ(loaded_custom_words, expected);
+  EXPECT_EQ(expected, loaded_custom_words);
 
-  custom_dictionary->WriteWordToCustomDictionary("foo");
-  expected.push_back("foo");
+  SpellcheckCustomDictionary::Change change;
+  change.AddWord("bar");
+  change.AddWord("foo");
 
-  custom_dictionary->WriteWordToCustomDictionary("bar");
+  UpdateDictionaryFile(change, path);
   expected.push_back("bar");
+  expected.push_back("foo");
 
   // The custom word list should include written words.
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
-  std::sort(expected.begin(), expected.end());
-  EXPECT_EQ(loaded_custom_words, expected);
-
-  // Load in another instance of SpellCheckService.
-  // The result should be the same.
-  SpellcheckService spellcheck_service2(profile_.get());
-  WordList loaded_custom_words2;
-  spellcheck_service2.GetCustomDictionary()->
-      LoadDictionaryIntoCustomWordList(&loaded_custom_words2);
-  EXPECT_EQ(loaded_custom_words2, expected);
-
-  custom_dictionary->EraseWordFromCustomDictionary("foo");
-  custom_dictionary->EraseWordFromCustomDictionary("bar");
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  loaded_custom_words = LoadDictionaryFile(path);
+  EXPECT_EQ(expected, loaded_custom_words);
+
+  change = SpellcheckCustomDictionary::Change();
+  change.RemoveWord("bar");
+  change.RemoveWord("foo");
+  UpdateDictionaryFile(change, path);
+  loaded_custom_words = LoadDictionaryFile(path);
   expected.clear();
-  EXPECT_EQ(loaded_custom_words, expected);
+  EXPECT_EQ(expected, loaded_custom_words);
 
   // Flush the loop now to prevent service init tasks from being run during
   // TearDown();
@@ -142,23 +219,23 @@ TEST_F(SpellcheckCustomDictionaryTest, MultiProfile) {
   WordList expected1;
   WordList expected2;
 
-  custom_dictionary->WriteWordToCustomDictionary("foo");
-  custom_dictionary->WriteWordToCustomDictionary("bar");
+  custom_dictionary->AddWord("foo");
+  custom_dictionary->AddWord("bar");
   expected1.push_back("foo");
   expected1.push_back("bar");
 
-  custom_dictionary2->WriteWordToCustomDictionary("hoge");
-  custom_dictionary2->WriteWordToCustomDictionary("fuga");
+  custom_dictionary2->AddWord("hoge");
+  custom_dictionary2->AddWord("fuga");
   expected2.push_back("hoge");
   expected2.push_back("fuga");
 
-  WordList actual1;
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&actual1);
+  WordList actual1 = custom_dictionary->GetWords();
+  std::sort(actual1.begin(), actual1.end());
   std::sort(expected1.begin(), expected1.end());
   EXPECT_EQ(actual1, expected1);
 
-  WordList actual2;
-  custom_dictionary2->LoadDictionaryIntoCustomWordList(&actual2);
+  WordList actual2 = custom_dictionary2->GetWords();
+  std::sort(actual2.begin(), actual2.end());
   std::sort(expected2.begin(), expected2.end());
   EXPECT_EQ(actual2, expected2);
 
@@ -167,19 +244,13 @@ TEST_F(SpellcheckCustomDictionaryTest, MultiProfile) {
   MessageLoop::current()->RunUntilIdle();
 }
 
-// Legacy empty dictionary should be converted to new format empty dicitonary.
+// Legacy empty dictionary should be converted to new format empty dictionary.
 TEST_F(SpellcheckCustomDictionaryTest, LegacyEmptyDictionaryShouldBeConverted) {
-  FilePath dictionary_path(
-      profile_->GetPath().Append(chrome::kCustomDictionaryFileName));
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  WordList loaded_custom_words;
+  FilePath path = profile_->GetPath().Append(chrome::kCustomDictionaryFileName);
 
   std::string content;
-  file_util::WriteFile(dictionary_path, content.c_str(), content.length());
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  file_util::WriteFile(path, content.c_str(), content.length());
+  WordList loaded_custom_words = LoadDictionaryFile(path);
   EXPECT_TRUE(loaded_custom_words.empty());
 
   // Flush the loop now to prevent service init tasks from being run during
@@ -191,18 +262,12 @@ TEST_F(SpellcheckCustomDictionaryTest, LegacyEmptyDictionaryShouldBeConverted) {
 // with two words.
 TEST_F(SpellcheckCustomDictionaryTest,
        LegacyDictionaryWithTwoWordsShouldBeConverted) {
-  FilePath dictionary_path(
-      profile_->GetPath().Append(chrome::kCustomDictionaryFileName));
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  WordList loaded_custom_words;
-  WordList expected;
+  FilePath path = profile_->GetPath().Append(chrome::kCustomDictionaryFileName);
 
-  std::string content = "foo\nbar";
-  file_util::WriteFile(dictionary_path, content.c_str(), content.length());
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  std::string content = "foo\nbar\nfoo\n";
+  file_util::WriteFile(path, content.c_str(), content.length());
+  WordList loaded_custom_words = LoadDictionaryFile(path);
+  WordList expected;
   expected.push_back("bar");
   expected.push_back("foo");
   EXPECT_EQ(expected, loaded_custom_words);
@@ -215,18 +280,12 @@ TEST_F(SpellcheckCustomDictionaryTest,
 // Words with spaces are illegal and should be removed.
 TEST_F(SpellcheckCustomDictionaryTest,
        IllegalWordsShouldBeRemovedFromDictionary) {
-  FilePath dictionary_path(
-      profile_->GetPath().Append(chrome::kCustomDictionaryFileName));
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  WordList loaded_custom_words;
-  WordList expected;
+  FilePath path = profile_->GetPath().Append(chrome::kCustomDictionaryFileName);
 
   std::string content = "foo\nfoo bar\nbar\nfoo bar";
-  file_util::WriteFile(dictionary_path, content.c_str(), content.length());
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  file_util::WriteFile(path, content.c_str(), content.length());
+  WordList loaded_custom_words = LoadDictionaryFile(path);
+  WordList expected;
   expected.push_back("bar");
   expected.push_back("foo");
   EXPECT_EQ(expected, loaded_custom_words);
@@ -236,35 +295,866 @@ TEST_F(SpellcheckCustomDictionaryTest,
   MessageLoop::current()->RunUntilIdle();
 }
 
-// Write to dicitonary should backup previous version and write the word to the
+// Write to dictionary should backup previous version and write the word to the
 // end of the dictionary. If the dictionary file is corrupted on disk, the
 // previous version should be reloaded.
 TEST_F(SpellcheckCustomDictionaryTest, CorruptedWriteShouldBeRecovered) {
-  FilePath dictionary_path(
-      profile_->GetPath().Append(chrome::kCustomDictionaryFileName));
-  SpellcheckService* spellcheck_service =
-      SpellcheckServiceFactory::GetForProfile(profile_.get());
-  SpellcheckCustomDictionary* custom_dictionary =
-      spellcheck_service->GetCustomDictionary();
-  WordList loaded_custom_words;
-  WordList expected;
+  FilePath path = profile_->GetPath().Append(chrome::kCustomDictionaryFileName);
 
   std::string content = "foo\nbar";
-  file_util::WriteFile(dictionary_path, content.c_str(), content.length());
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  file_util::WriteFile(path, content.c_str(), content.length());
+  WordList loaded_custom_words = LoadDictionaryFile(path);
+  WordList expected;
   expected.push_back("bar");
   expected.push_back("foo");
   EXPECT_EQ(expected, loaded_custom_words);
 
-  custom_dictionary->WriteWordToCustomDictionary("baz");
+  SpellcheckCustomDictionary::Change change;
+  change.AddWord("baz");
+  UpdateDictionaryFile(change, path);
   content.clear();
-  file_util::ReadFileToString(dictionary_path, &content);
+  file_util::ReadFileToString(path, &content);
   content.append("corruption");
-  file_util::WriteFile(dictionary_path, content.c_str(), content.length());
-  custom_dictionary->LoadDictionaryIntoCustomWordList(&loaded_custom_words);
+  file_util::WriteFile(path, content.c_str(), content.length());
+  loaded_custom_words = LoadDictionaryFile(path);
   EXPECT_EQ(expected, loaded_custom_words);
 
   // Flush the loop now to prevent service init tasks from being run during
   // TearDown();
   MessageLoop::current()->RunUntilIdle();
 }
+
+TEST_F(SpellcheckCustomDictionaryTest,
+       GetAllSyncDataAccuratelyReflectsDictionaryState) {
+  SpellcheckCustomDictionary* dictionary =
+      SpellcheckServiceFactory::GetForProfile(
+          profile_.get())->GetCustomDictionary();
+
+  syncer::SyncDataList data = dictionary->GetAllSyncData(syncer::DICTIONARY);
+  EXPECT_TRUE(data.empty());
+
+  EXPECT_TRUE(dictionary->AddWord("foo"));
+  EXPECT_TRUE(dictionary->AddWord("bar"));
+
+  data = dictionary->GetAllSyncData(syncer::DICTIONARY);
+  EXPECT_EQ(2UL, data.size());
+  std::vector<std::string> words;
+  words.push_back("foo");
+  words.push_back("bar");
+  for (size_t i = 0; i < data.size(); i++) {
+    EXPECT_TRUE(data[i].GetSpecifics().has_dictionary());
+    EXPECT_EQ(syncer::DICTIONARY, data[i].GetDataType());
+    EXPECT_EQ(words[i], data[i].GetTag());
+    EXPECT_EQ(words[i], data[i].GetSpecifics().dictionary().word());
+  }
+
+  EXPECT_TRUE(dictionary->RemoveWord("foo"));
+  EXPECT_TRUE(dictionary->RemoveWord("bar"));
+
+  data = dictionary->GetAllSyncData(syncer::DICTIONARY);
+  EXPECT_TRUE(data.empty());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, GetAllSyncDataHasLimit) {
+  SpellcheckCustomDictionary* dictionary =
+      SpellcheckServiceFactory::GetForProfile(
+          profile_.get())->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS - 1;
+       i++) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+  }
+  Apply(*dictionary, change);
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS - 1,
+            dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS - 1,
+            dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+
+  dictionary->AddWord("baz");
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+
+  dictionary->AddWord("bar");
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+
+  dictionary->AddWord("snafoo");
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 2,
+            dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, ProcessSyncChanges) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* dictionary =
+      spellcheck_service->GetCustomDictionary();
+
+  dictionary->AddWord("foo");
+  dictionary->AddWord("bar");
+
+  syncer::SyncChangeList changes;
+  {
+    // Add existing word.
+    std::string word = "foo";
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    changes.push_back(syncer::SyncChange(
+        FROM_HERE,
+        syncer::SyncChange::ACTION_ADD,
+        syncer::SyncData::CreateLocalData(word, word, specifics)));
+  }
+  {
+    // Add invalid word.
+    std::string word = "foo bar";
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    changes.push_back(syncer::SyncChange(
+        FROM_HERE,
+        syncer::SyncChange::ACTION_ADD,
+        syncer::SyncData::CreateLocalData(word, word, specifics)));
+  }
+  {
+    // Add valid word.
+    std::string word = "baz";
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    changes.push_back(syncer::SyncChange(
+        FROM_HERE,
+        syncer::SyncChange::ACTION_ADD,
+        syncer::SyncData::CreateLocalData(word, word, specifics)));
+  }
+  {
+    // Remove missing word.
+    std::string word = "snafoo";
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    changes.push_back(syncer::SyncChange(
+        FROM_HERE,
+        syncer::SyncChange::ACTION_DELETE,
+        syncer::SyncData::CreateLocalData(word, word, specifics)));
+  }
+  {
+    // Remove existing word.
+    std::string word = "bar";
+    sync_pb::EntitySpecifics specifics;
+    specifics.mutable_dictionary()->set_word(word);
+    changes.push_back(syncer::SyncChange(
+        FROM_HERE,
+        syncer::SyncChange::ACTION_DELETE,
+        syncer::SyncData::CreateLocalData(word, word, specifics)));
+  }
+
+  EXPECT_FALSE(dictionary->ProcessSyncChanges(FROM_HERE, changes).IsSet());
+
+  const chrome::spellcheck_common::WordList& words = dictionary->GetWords();
+  EXPECT_EQ(2UL, words.size());
+  EXPECT_EQ(words.end(), std::find(words.begin(), words.end(), "bar"));
+  EXPECT_NE(words.end(), std::find(words.begin(), words.end(), "foo"));
+  EXPECT_NE(words.end(), std::find(words.begin(), words.end(), "baz"));
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, MergeDataAndStartSyncing) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, change);
+
+  SpellcheckCustomDictionary::Change change2;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2;
+       ++i) {
+    change2.AddWord("bar" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary2, change2);
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  WordList words = custom_dictionary->GetWords();
+  WordList words2 = custom_dictionary2->GetWords();
+  EXPECT_EQ(words.size(), words2.size());
+
+  std::sort(words.begin(), words.end());
+  std::sort(words2.begin(), words2.end());
+  EXPECT_EQ(words, words2);
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryTooBigBeforeSyncing) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, change);
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryTooBigAndServerFull) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  SpellcheckCustomDictionary::Change change2;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+    change2.AddWord("bar" + base::Uint64ToString(i));
+  }
+  change.AddWord("foo");
+  Apply(*custom_dictionary, change);
+  Apply(*custom_dictionary2, change2);
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS * 2 + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, ServerTooBig) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  SpellcheckCustomDictionary::Change change2;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+    change2.AddWord("bar" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, change);
+  Apply(*custom_dictionary2, change2);
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary2->GetWords().size());
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      GetAllSyncDataNoLimit(custom_dictionary2),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS * 2 + 2,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryTooBigToStartSyncing) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS - 1;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, change);
+
+  custom_dictionary2->AddWord("bar");
+  custom_dictionary2->AddWord("baz");
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryTooBigToContiueSyncing) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  SpellcheckCustomDictionary::Change change;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS - 1;
+       ++i) {
+    change.AddWord("foo" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, change);
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  custom_dictionary->AddWord("bar");
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  custom_dictionary->AddWord("baz");
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, LoadAfterSyncStart) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  custom_dictionary->AddWord("foo");
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  WordList custom_words;
+  custom_words.push_back("bar");
+  OnLoaded(*custom_dictionary, custom_words);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(2UL, custom_dictionary->GetWords().size());
+  EXPECT_EQ(2UL, custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(2UL, custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(2UL, custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, LoadAfterSyncStartTooBigToSync) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  custom_dictionary->AddWord("foo");
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  WordList custom_words;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS;
+       ++i) {
+    custom_words.push_back("foo" + base::Uint64ToString(i));
+  }
+  OnLoaded(*custom_dictionary, custom_words);
+  EXPECT_EQ(0, error_counter);
+  EXPECT_FALSE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS + 1,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, LoadDuplicatesAfterSync) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  WordList to_add;
+  for (size_t i = 0;
+       i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2;
+       ++i) {
+    to_add.push_back("foo" + base::Uint64ToString(i));
+  }
+  Apply(*custom_dictionary, SpellcheckCustomDictionary::Change(to_add));
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  OnLoaded(*custom_dictionary, to_add);
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2,
+            custom_dictionary->GetWords().size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2,
+            custom_dictionary2->GetWords().size());
+
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2,
+            custom_dictionary->GetAllSyncData(syncer::DICTIONARY).size());
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS / 2,
+            custom_dictionary2->GetAllSyncData(syncer::DICTIONARY).size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryLoadNotification) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+
+  DictionaryObserverCounter observer;
+  custom_dictionary->AddObserver(&observer);
+
+  WordList custom_words;
+  custom_words.push_back("foo");
+  custom_words.push_back("bar");
+  OnLoaded(*custom_dictionary, custom_words);
+
+  EXPECT_GE(observer.loads(), 1);
+  EXPECT_LE(observer.loads(), 2);
+  EXPECT_EQ(0, observer.changes());
+
+  custom_dictionary->RemoveObserver(&observer);
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryAddWordNotification) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+
+  OnLoaded(*custom_dictionary, WordList());
+
+  DictionaryObserverCounter observer;
+  custom_dictionary->AddObserver(&observer);
+
+  EXPECT_TRUE(custom_dictionary->AddWord("foo"));
+  EXPECT_TRUE(custom_dictionary->AddWord("bar"));
+  EXPECT_FALSE(custom_dictionary->AddWord("bar"));
+
+  EXPECT_EQ(2, observer.changes());
+
+  custom_dictionary->RemoveObserver(&observer);
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionaryRemoveWordNotification) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+
+  OnLoaded(*custom_dictionary, WordList());
+
+  EXPECT_TRUE(custom_dictionary->AddWord("foo"));
+  EXPECT_TRUE(custom_dictionary->AddWord("bar"));
+
+  DictionaryObserverCounter observer;
+  custom_dictionary->AddObserver(&observer);
+
+  EXPECT_TRUE(custom_dictionary->RemoveWord("foo"));
+  EXPECT_TRUE(custom_dictionary->RemoveWord("bar"));
+  EXPECT_FALSE(custom_dictionary->RemoveWord("baz"));
+
+  EXPECT_EQ(2, observer.changes());
+
+  custom_dictionary->RemoveObserver(&observer);
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+TEST_F(SpellcheckCustomDictionaryTest, DictionarySyncNotification) {
+  SpellcheckService* spellcheck_service =
+      SpellcheckServiceFactory::GetForProfile(profile_.get());
+  SpellcheckCustomDictionary* custom_dictionary =
+      spellcheck_service->GetCustomDictionary();
+  TestingProfile profile2;
+  SpellcheckService* spellcheck_service2 =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &profile2, &BuildSpellcheckService));
+  SpellcheckCustomDictionary* custom_dictionary2 =
+      spellcheck_service2->GetCustomDictionary();
+
+  OnLoaded(*custom_dictionary, WordList());
+  OnLoaded(*custom_dictionary2, WordList());
+
+  custom_dictionary->AddWord("foo");
+  custom_dictionary->AddWord("bar");
+  custom_dictionary2->AddWord("foo");
+  custom_dictionary2->AddWord("baz");
+
+  DictionaryObserverCounter observer;
+  custom_dictionary->AddObserver(&observer);
+
+  DictionaryObserverCounter observer2;
+  custom_dictionary2->AddObserver(&observer2);
+
+  int error_counter = 0;
+  EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+      syncer::DICTIONARY,
+      custom_dictionary2->GetAllSyncData(syncer::DICTIONARY),
+      scoped_ptr<syncer::SyncChangeProcessor>(
+          new SyncChangeProcessorDelegate(custom_dictionary2)),
+      scoped_ptr<syncer::SyncErrorFactory>(
+          new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+  EXPECT_EQ(0, error_counter);
+  EXPECT_TRUE(custom_dictionary->IsSyncing());
+
+  EXPECT_EQ(1, observer.changes());
+  EXPECT_EQ(1, observer2.changes());
+
+  custom_dictionary->RemoveObserver(&observer);
+  custom_dictionary2->RemoveObserver(&observer2);
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}
+
+// The server has maximum number of words and the client has maximum number of
+// different words before association time. No new words should be pushed to the
+// sync server upon association. The client should accept words from the sync
+// server, however.
+TEST_F(SpellcheckCustomDictionaryTest, DictionarySyncLimit) {
+  TestingProfile server_profile;
+  SpellcheckService* server_spellcheck_service =
+      static_cast<SpellcheckService*>(
+          SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+              &server_profile, &BuildSpellcheckService));
+
+  // Here, |server_custom_dictionary| plays the role of the sync server.
+  SpellcheckCustomDictionary* server_custom_dictionary =
+      server_spellcheck_service->GetCustomDictionary();
+
+  // Upload the maximum number of words to the sync server.
+  {
+    SpellcheckService* spellcheck_service =
+        SpellcheckServiceFactory::GetForProfile(profile_.get());
+    SpellcheckCustomDictionary* custom_dictionary =
+        spellcheck_service->GetCustomDictionary();
+
+    SpellcheckCustomDictionary::Change change;
+    for (size_t i = 0;
+         i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS;
+         ++i) {
+      change.AddWord("foo" + base::Uint64ToString(i));
+    }
+    Apply(*custom_dictionary, change);
+
+    int error_counter = 0;
+    EXPECT_FALSE(custom_dictionary->MergeDataAndStartSyncing(
+        syncer::DICTIONARY,
+        server_custom_dictionary->GetAllSyncData(syncer::DICTIONARY),
+        scoped_ptr<syncer::SyncChangeProcessor>(
+            new SyncChangeProcessorDelegate(server_custom_dictionary)),
+        scoped_ptr<syncer::SyncErrorFactory>(
+            new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+    EXPECT_EQ(0, error_counter);
+    EXPECT_TRUE(custom_dictionary->IsSyncing());
+    EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+              custom_dictionary->GetWords().size());
+  }
+
+  // The sync server now has the maximum number of words.
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            server_custom_dictionary->GetWords().size());
+
+  // Associate the sync server with a client that also has the maximum number of
+  // words, but all of these words are different from the ones on the sync
+  // server.
+  {
+    TestingProfile client_profile;
+    SpellcheckService* client_spellcheck_service =
+        static_cast<SpellcheckService*>(
+            SpellcheckServiceFactory::GetInstance()->SetTestingFactoryAndUse(
+                &client_profile, &BuildSpellcheckService));
+
+    // Here, |client_custom_dictionary| plays the role of the client.
+    SpellcheckCustomDictionary* client_custom_dictionary =
+        client_spellcheck_service->GetCustomDictionary();
+
+    // Add the maximum number of words to the client. These words are all
+    // different from those on the server.
+    SpellcheckCustomDictionary::Change change;
+    for (size_t i = 0;
+         i < chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS;
+         ++i) {
+      change.AddWord("bar" + base::Uint64ToString(i));
+    }
+    Apply(*client_custom_dictionary, change);
+
+    // Associate the server and the client.
+    int error_counter = 0;
+    EXPECT_FALSE(client_custom_dictionary->MergeDataAndStartSyncing(
+        syncer::DICTIONARY,
+        server_custom_dictionary->GetAllSyncData(syncer::DICTIONARY),
+        scoped_ptr<syncer::SyncChangeProcessor>(
+            new SyncChangeProcessorDelegate(server_custom_dictionary)),
+        scoped_ptr<syncer::SyncErrorFactory>(
+            new SyncErrorFactoryStub(&error_counter))).error().IsSet());
+    EXPECT_EQ(0, error_counter);
+    EXPECT_FALSE(client_custom_dictionary->IsSyncing());
+    EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS * 2,
+              client_custom_dictionary->GetWords().size());
+
+    // Flush the loop now to prevent service init tasks from being run during
+    // TearDown();
+    MessageLoop::current()->RunUntilIdle();
+  }
+
+  // The sync server should not receive more words, because it has the maximum
+  // number of words already.
+  EXPECT_EQ(chrome::spellcheck_common::MAX_SYNCABLE_DICTIONARY_WORDS,
+            server_custom_dictionary->GetWords().size());
+
+  // Flush the loop now to prevent service init tasks from being run during
+  // TearDown();
+  MessageLoop::current()->RunUntilIdle();
+}