[MD History] Refactor history.html into a history-app element.

chrome/test/data/webui/md_history/md_history_browsertest.js

Index: chrome/test/data/webui/md_history/md_history_browsertest.js
diff --git a/chrome/test/data/webui/md_history/md_history_browsertest.js b/chrome/test/data/webui/md_history/md_history_browsertest.js
index a493c380a57f873c57093a37715e963cef2d10e7..b260e53a382d2f70c565cd7f56e83a0ceb7c1f4f 100644
--- a/chrome/test/data/webui/md_history/md_history_browsertest.js
+++ b/chrome/test/data/webui/md_history/md_history_browsertest.js
@@ -43,9 +43,7 @@ MaterialHistoryBrowserTest.prototype = {
     suiteSetup(function() {
       // Wait for each of the top-level elements to be upgraded.
       return Promise.all([
-        waitForUpgrade($('history-list')),
-        waitForUpgrade($('toolbar')),
-        waitForUpgrade($('history-synced-device-manager')),
+        waitForUpgrade($('history-app')),
       ]);
     });
   },