MD WebUI: Add loading spinner to cr-toolbar, hook into MD History toolbar

chrome/browser/resources/md_history/app.js

Index: chrome/browser/resources/md_history/app.js
diff --git a/chrome/browser/resources/md_history/app.js b/chrome/browser/resources/md_history/app.js
index a16204324a4bf4384f0b4b5fb8b3d1c2846d2305..fa0a15669186af4175b3cb2c3629b0a4966aa1d0 100644
--- a/chrome/browser/resources/md_history/app.js
+++ b/chrome/browser/resources/md_history/app.js
@@ -40,6 +40,8 @@ Polymer({
           querying: true,
           searchTerm: '',
           results: null,
+          // Whether the most recent query was incremental.
+          incremental: false,

[dpapad, 2016/06/08 00:07:35]

Shouldn't the QueryState typedef also be upadated? 

[tsergeant, 2016/06/08 02:53:54]

Done.

           info: null,
           range: HistoryRange.ALL_TIME,
           // TODO(calamity): Make history toolbar buttons change the offset.
@@ -175,6 +177,7 @@ Polymer({
       return;
 
     this.set('queryState_.querying', true);
+    this.set('queryState_.incremental', incremental);
 
     var queryState = this.queryState_;
 
@@ -211,7 +214,20 @@ Polymer({
     return selectedPage;
   },
 
-  syncedTabsSelected_(selectedPage) {
+  syncedTabsSelected_: function(selectedPage) {

[dpapad, 2016/06/08 00:07:35]

Same here.

[tsergeant, 2016/06/08 02:53:54]

Done.

     return selectedPage == 'history-synced-device-manager';
+  },
+
+  /**
+   * True if the toolbar should show a loading spinner. True when the backend is
+   * querying a new search term.
+   * @param {boolean} querying
+   * @param {boolean} incremental
+   * @param {string} searchTerm
+   * @return {boolean}

[dpapad, 2016/06/08 00:07:36]

Nit: Move the comment at lines 222-223 here, as follows.

@return {boolean} Whether a spinner should be shown
    (implies that the backend is querying a new search term).

[tsergeant, 2016/06/08 02:53:54]

Done.

+   * @private
+   */
+  shouldShowSpinner_: function(querying, incremental, searchTerm) {
+    return querying && !incremental && searchTerm != '';
   }
 });