Clean up how we handle themes in the extensions system and management API....

chrome/test/data/extensions/management/themes/undo2.js

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+
+var test_steps = [
+  ["enable", "iamefpfkojoapidjnbafmgkgncegbkad"],
+  ["disable", "pjpgmfcmabopnnfonnhmdjglfpjjfkbf"],
+  send("step1")
+];
+
+chrome.management.getAll(function(items) {
+  var enabled_theme = null;
+  for (var i = 0; i < items.length; i++) {
+    var item = items[i];
+    if (!item.isTheme) {
+      continue;
+    }
+    if (item.enabled) {
+        if (enabled_theme) {
+          console.log("error: more than 1 enabled theme!");
+          return;
+        }
+      enabled_theme = item;
+    }
+  }
+  if (enabled_theme.id != "pjpgmfcmabopnnfonnhmdjglfpjjfkbf") {
+    console.log("Found unexpected theme enabled : " + enabled_theme.id);
+    return;
+  }
+  chrome.test.sendMessage("ready");
+});
+