MD History: Add spinners when new data is loading or searching

chrome/browser/resources/md_history/history_toolbar.html

Index: chrome/browser/resources/md_history/history_toolbar.html
diff --git a/chrome/browser/resources/md_history/history_toolbar.html b/chrome/browser/resources/md_history/history_toolbar.html
index ea78ae2531d49b86025bd9ea70aeff915afe15de..23642458a46e26b5bded979883008d441b6c1a8a 100644
--- a/chrome/browser/resources/md_history/history_toolbar.html
+++ b/chrome/browser/resources/md_history/history_toolbar.html
@@ -2,6 +2,7 @@
 <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/polymer/v1_0/paper-spinner/paper-spinner.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_search_field/cr_search_field.html">
 <link rel="import" href="chrome://history/shared_style.html">
 
@@ -41,6 +42,11 @@
         -webkit-padding-end: 20px;
       }
 
+      paper-spinner.search {
+        height: 20px;
+        width: 20px;
+      }
+
       #items {
         margin: 0 auto;
         max-width: var(--card-max-width);
@@ -85,6 +91,10 @@
     <div id="toolbar-container">
       <div id="main-content" hidden$="[[itemsSelected_]]">
         <h1 id="title">$i18n{title}</h1>
+        <div id="searching-spinner"  hidden$="[[!searching_]]">

[tsergeant, 2016/04/18 01:26:36]

Nit: There's an extra space in here.

[lshang, 2016/04/22 01:25:03]

Done.

+          <paper-spinner class="search" active>
+          </paper-spinner>
+        </div>
         <cr-search-field id="search-input" label="$i18n{search}"
             clear-label="$i18n{clearSearch}">
         </cr-search-field>