Show dictionary changes in chrome://settings/editDictionary as changes come in

chrome/browser/ui/webui/options/edit_dictionary_browsertest.js

Index: chrome/browser/ui/webui/options/edit_dictionary_browsertest.js
diff --git a/chrome/browser/ui/webui/options/edit_dictionary_browsertest.js b/chrome/browser/ui/webui/options/edit_dictionary_browsertest.js
index 0e1522149982debd094ed4bc2b05e5f0b4f740db..ad8ce8052cb0af597a5d4cc537b36b144433c779 100644
--- a/chrome/browser/ui/webui/options/edit_dictionary_browsertest.js
+++ b/chrome/browser/ui/webui/options/edit_dictionary_browsertest.js
@@ -35,6 +35,7 @@ EditDictionaryWebUITest.prototype = {
   },
 };
 
+// Verify that users can add and remove words in the dictionary.
 TEST_F('EditDictionaryWebUITest', 'testAddRemoveWords', function() {
   var testWord = 'foo';
   $('language-dictionary-overlay-word-list').querySelector('input').value =
@@ -54,6 +55,7 @@ TEST_F('EditDictionaryWebUITest', 'testAddRemoveWords', function() {
   EditDictionaryOverlay.getWordListForTesting().deleteItemAtIndex(0);
 });
 
+// Verify that users can search words in the dictionary.
 TEST_F('EditDictionaryWebUITest', 'testSearch', function() {
   EditDictionaryOverlay.setWordList(['foo', 'bar']);
   expectEquals(3, EditDictionaryOverlay.getWordListForTesting().items.length);
@@ -73,3 +75,50 @@ TEST_F('EditDictionaryWebUITest', 'testSearch', function() {
   fakeSearchEvent(searchField, '');
   expectEquals(3, EditDictionaryOverlay.getWordListForTesting().items.length);
 });
+
+// Verify that dictionary shows newly added words that arrived in a
+// notification, but ignores duplicate add notifications.
+TEST_F('EditDictionaryWebUITest', 'testAddNotification', function() {
+  // Begin with an empty dictionary.
+  EditDictionaryOverlay.setWordList([]);
+  expectEquals(1, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // User adds word 'foo'.
+  EditDictionaryOverlay.getWordListForTesting().addDictionaryWord_('foo');
+  expectEquals(2, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // Backend notifies UI that the word 'foo' has been added. UI ignores this
+  // notification, because the word is displayed immediately after user added
+  // it.
+  EditDictionaryOverlay.updateWords(['foo'], []);
+  expectEquals(2, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // Backend notifies UI that the words 'bar' and 'baz' were added. UI shows
+  // these new words.
+  EditDictionaryOverlay.updateWords(['bar', 'baz'], []);
+  expectEquals(4, EditDictionaryOverlay.getWordListForTesting().items.length);
+});
+
+// Verify that dictionary hides newly removed words that arrived in a
+// notification, but ignores duplicate remove notifications.
+TEST_F('EditDictionaryWebUITest', 'testRemoveNotification', function() {
+  // Begin with a dictionary with words 'foo', 'bar', 'baz', and 'baz'. The
+  // second instance of 'baz' appears because the user added the word twice.
+  // The backend keeps only one copy of the word.
+  EditDictionaryOverlay.setWordList(['foo', 'bar', 'baz', 'baz']);
+  expectEquals(5, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // User deletes the second instance of 'baz'.
+  EditDictionaryOverlay.getWordListForTesting().deleteItemAtIndex(3);
+  expectEquals(4, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // Backend notifies UI that the word 'baz' has been removed. UI ignores this
+  // notification.
+  EditDictionaryOverlay.updateWords([], ['baz']);
+  expectEquals(4, EditDictionaryOverlay.getWordListForTesting().items.length);
+
+  // Backend notifies UI that words 'foo' and 'bar' have been removed. UI
+  // removes these words.
+  EditDictionaryOverlay.updateWords([], ['foo', 'bar']);
+  expectEquals(2, EditDictionaryOverlay.getWordListForTesting().items.length);
+});