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

chrome/browser/resources/md_history/history_list.html

Index: chrome/browser/resources/md_history/history_list.html
diff --git a/chrome/browser/resources/md_history/history_list.html b/chrome/browser/resources/md_history/history_list.html
index 9d38f3d802f472fccff903c1290eda81ad65e483..bda8137bde8bc67641ad08a456808e11bc47e852 100644
--- a/chrome/browser/resources/md_history/history_list.html
+++ b/chrome/browser/resources/md_history/history_list.html
@@ -1,6 +1,7 @@
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-list/iron-list.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-item/paper-item.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-spinner/paper-spinner.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_shared_menu/cr_shared_menu.html">
 <link rel="import" href="chrome://history/constants.html">
 <link rel="import" href="chrome://history/history_item.html">
@@ -13,6 +14,7 @@
       :host {
         display: flex;
         flex-direction: column;
+        position: relative;
       }
 
       #infinite-list {
@@ -20,6 +22,15 @@
         padding-top: var(--first-card-padding-top);
       }
 
+      #loading-spinner {
+        bottom: 15px;
+        left: 0;
+        margin: 0 auto;
+        position: absolute;
+        right: 0;
+        width: 28px;
+      }
+
       paper-item {
         -webkit-user-select: none;
         cursor: pointer;
@@ -49,6 +60,9 @@
         </history-item>
       </template>
     </iron-list>
+    <div id="loading-spinner" hidden$="[[!loading_]]">
+      <paper-spinner alt=$i18n{loading} active></paper-spinner>

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

Nit: This should have quotes

alt="$i18n{loading}"

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

Done.

+    </div>
     <cr-shared-menu id="sharedMenu">
       <paper-item id="menuMoreButton" on-tap="onMoreFromSiteTap_">
         $i18n{moreFromSite}