Add a policy to hide the Web Store on new tabs.

chrome/browser/resources/ntp4/apps_page.js

Index: chrome/browser/resources/ntp4/apps_page.js
diff --git a/chrome/browser/resources/ntp4/apps_page.js b/chrome/browser/resources/ntp4/apps_page.js
index 21f5062ab97680733e16d39453d3235d37c38621..aefe0c20a2d0656dc9698ece53b4aee700dc6328 100644
--- a/chrome/browser/resources/ntp4/apps_page.js
+++ b/chrome/browser/resources/ntp4/apps_page.js
@@ -668,6 +668,12 @@ cr.define('ntp', function() {
      * @param {boolean} animate Whether to animate the insertion.
      */
     insertApp: function(appData, animate) {
+      // Don't show the web store icon if policy so dictates.
+      if (appData.is_webstore &&
+          loadTimeData.getBoolean('isWebStoreIconHidden')) {
+        return;
+      }
+
       var index = this.tileElements_.length;
       for (var i = 0; i < this.tileElements_.length; i++) {
         if (appData.app_launch_ordinal <