Initially load new_tab.css with a timestamp for chrome://apps.

This is what incognito_tab.html already does. Changing the url to add a
timestamp query on DOMContentLoaded caused a FoUC.

BUG=681495
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2647653002
Cr-Commit-Position: refs/heads/master@{#445285}
(cherry picked from commit babe852)

Review-Url: https://codereview.chromium.org/2650683002 .
Cr-Commit-Position: refs/branch-heads/2987@{#18}
Cr-Branched-From: ad51088-refs/heads/master@{#444943}

chrome/browser/resources/ntp4/new_tab.html

@@ -28,8 +28,11 @@
 <link rel="stylesheet" href="nav_dot.css">
 <link rel="stylesheet" href="new_tab.css">
 <link rel="stylesheet" href="tile_page.css">
-<link id="themecss" rel="stylesheet" href="chrome://theme/css/new_tab_theme.css">
-
+<script>
+// Until themes can clear the cache, force-reload the theme stylesheet.
+document.write('<link id="themecss" rel="stylesheet" ' +
+               'href="chrome://theme/css/new_tab_theme.css?' + Date.now() + '">');
+</script>
 <script src="../../../../ui/webui/resources/js/action_link.js"></script>
 <script src="../../../../ui/webui/resources/js/event_tracker.js"></script>
 <script src="../../../../ui/webui/resources/js/util.js"></script>

chrome/browser/resources/ntp4/new_tab.js

@@ -90,9 +90,6 @@ cr.define('ntp', function() {
     }
     measureNavDots();
 
-    // Load the current theme colors.
-    themeChanged();
-
     newTabView = new NewTabView();
 
     if (!loadTimeData.getBoolean('showWebStoreIcon')) {