MD History: Hook all elements into the page and add tests.

chrome/browser/resources/md_history/history_toolbar.html

+<link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
+<link rel="import" href="chrome://resources/cr_elements/cr_search_field/cr_search_field.html">
+
+<dom-module id="history-toolbar">
+  <template>
+
+    <style>
+      :host {
+        @apply(--layout-center);
+        @apply(--layout-horizontal);
+        background: #3f5566;
+        color: #fff;
+        height: 56px;
+        transition: background-color 150ms;
+        width: 100%;
+      }
+
+      :host([items-selected_]) {
+        background: #48f;
+      }
+
+      h1 {
+        @apply(--layout-flex);
+        font-size: 16px;
+        font-weight: 400;
+        padding-left: 24px;
+      }
+
+      #items {
+        @apply(--layout-center);
+        @apply(--layout-horizontal);
+        margin: 0 auto;
+        max-width: 960px;
+        width: 100%;
+      }
+
+      #number-selected {
+        @apply(--layout-flex);
+      }
+
+      paper-icon-button {
+        height: 36px;
+        margin: 0 24px 0 2px;
+        min-width: 36px;
+        width: 36px;
+      }
+    </style>
+
+    <template is="dom-if" if="{{!itemsSelected_}}">
+      <h1 i18n-content="title" id="title"></h1>
+      <cr-search-field id="search-input"
+          i18n-values="label:search;clear-label:clearSearch"></cr-search-field>
+    </template>
+
+    <template is="dom-if" if="{{itemsSelected_}}">
+      <div id="items">
+        <paper-icon-button icon="clear" id="cancel-icon-button"
+            on-tap="clearSelection">

[tsergeant, 2016/01/25 00:40:20]

clearSelection -> onClearSelectionTap_

(onThingAction_ is the event naming convention for webui_)

[hsampson, 2016/01/25 02:14:01]

Done.

+        </paper-icon-button>
+        <!-- TODO: change "selected" and number to an i18n (or equivalent)
+              string -->
+        <div id="number-selected">{{count}} selected</div>
+        <paper-button id="cancel-button" on-tap="clearSelection">
+          CANCEL
+        </paper-button>
+        <paper-button id="delete-button">DELETE</paper-button>
+      </div>
+    </template>
+
+  </template>
+  <script src="chrome://history/history_toolbar.js"></script>
+</dom-module>