[Extensions] Update Error Console UI

chrome/browser/resources/extensions/extension_code.js

Index: chrome/browser/resources/extensions/extension_code.js
diff --git a/chrome/browser/resources/extensions/extension_code.js b/chrome/browser/resources/extensions/extension_code.js
index 1e95c88d9ea7ac19a7c8317ddccb83171086015c..255909d6352baaee77c0b2158ea9318387c587c3 100644
--- a/chrome/browser/resources/extensions/extension_code.js
+++ b/chrome/browser/resources/extensions/extension_code.js
@@ -43,19 +43,20 @@ cr.define('extensions', function() {
       // Clear any remnant content, so we don't have multiple code listed.
       this.clear();
 
-      var sourceDiv = document.createElement('div');
-      sourceDiv.classList.add('extension-code-source');
-      this.appendChild(sourceDiv);
-
       // If there's no code, then display an appropriate message.
       if (!code ||
           (!code.highlight && !code.beforeHighlight && !code.afterHighlight)) {
         var span = document.createElement('span');
+        span.classList.add('extension-code-empty');
         span.textContent = emptyMessage;
-        sourceDiv.appendChild(span);
+        this.appendChild(span);
         return;
       }
 
+      var sourceDiv = document.createElement('div');
+      sourceDiv.classList.add('extension-code-source');
+      this.appendChild(sourceDiv);
+
       var lineCount = 0;
       var createSpan = function(source, isHighlighted) {
         lineCount += source.split('\n').length - 1;