MD History: Use iron-a11y-announcer to announce search result messages

chrome/browser/resources/md_history/list_container.js

Index: chrome/browser/resources/md_history/list_container.js
diff --git a/chrome/browser/resources/md_history/list_container.js b/chrome/browser/resources/md_history/list_container.js
index a0b7efeb8161e0eb0c198534a84da4dc04898525..f751a8345d1f38dc8b4db1e5d4a1185d31437a5e 100644
--- a/chrome/browser/resources/md_history/list_container.js
+++ b/chrome/browser/resources/md_history/list_container.js
@@ -42,8 +42,11 @@ Polymer({
     this.closeMenu_();
 
     if (info.term && !this.queryState.incremental) {
-      announceAccessibleMessage(
-          md_history.HistoryItem.searchResultsTitle(results.length, info.term));
+      Polymer.IronA11yAnnouncer.requestAvailability();
+      this.fire('iron-announce', {
+        text:
+            md_history.HistoryItem.searchResultsTitle(results.length, info.term)
+      });
     }
 
     if (this.selectedPage_ == 'grouped-list') {