MD WebUI: rework how clearing search works

ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js

Index: ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js
diff --git a/ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js b/ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js
index 03c74d8e5a34b76bda14a937e731634d264d3696..e028176f525f921297a7f76d48da79a6ac8842b1 100644
--- a/ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js
+++ b/ui/webui/resources/cr_elements/cr_search_field/cr_search_field.js
@@ -4,5 +4,21 @@
 
 var SearchField = Polymer({
   is: 'cr-search-field',
-  behaviors: [CrSearchFieldBehavior]
+
+  behaviors: [CrSearchFieldBehavior],
+
+  properties: {
+    value_: String,
+  },
+
+  /** @private */
+  clearSearch_: function() {
+    this.setValue('');
+    this.$.searchInput.focus();
+  },
+
+  /** @private */
+  toggleShowingSearch_: function() {
+    this.showingSearch = !this.showingSearch;
+  },
 });