MD History: add shortcuts for search

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

Index: chrome/test/data/webui/md_history/history_toolbar_test.js
diff --git a/chrome/test/data/webui/md_history/history_toolbar_test.js b/chrome/test/data/webui/md_history/history_toolbar_test.js
index 86f6f02b4b08ee39cda66844f1a1a2f62825b14a..0d502795ad2505a88d8b82ac8b635aba5f412685 100644
--- a/chrome/test/data/webui/md_history/history_toolbar_test.js
+++ b/chrome/test/data/webui/md_history/history_toolbar_test.js
@@ -52,6 +52,26 @@ cr.define('md_history.history_toolbar_test', function() {
         toolbar.$$('cr-toolbar').fire('search-changed', 'Test');
       });
 
+      test('shortcuts to open search field', function() {
+        var field = toolbar.$['main-toolbar'].getSearchField();
+        assertFalse(field.showingSearch);
+
+        MockInteractions.pressAndReleaseKeyOn(
+            field.$.searchInput, 191, '', '/');

[tsergeant, 2016/07/08 00:26:05]

In MockInteractions.pressAndReleaseKeyOn, it's probably better to not target
`field.$.searchInput`, since that's kind of like saying that the events will
work if the search input is already focused.

It's better to check that the events can be fired from anywhere on the document
and still work:

MockInteractions.pressAndReleaseKeyOn(document, 191, ...)

[lshang, 2016/07/08 05:37:24]

Done.

+        assertTrue(field.showingSearch);
+        assertEquals(field.$.searchInput, field.root.activeElement);
+
+        MockInteractions.pressAndReleaseKeyOn(
+            field.$.searchInput, 27, '', 'Escape');
+        assertFalse(field.showingSearch, 'Pressing escape closes field.');
+        assertNotEquals(field.$.searchInput, field.root.activeElement);
+
+        MockInteractions.pressAndReleaseKeyOn(

[tsergeant, 2016/07/08 00:26:05]

As above, use document here.

[lshang, 2016/07/08 05:37:24]

Done.

+            field.$.searchInput, 70, 'ctrl', 'f');
+        assertTrue(field.showingSearch);
+        assertEquals(field.$.searchInput, field.root.activeElement);
+     });
+
       teardown(function() {
         element.historyData_ = [];
         element.searchedTerm = '';