[Extensions Toolbar] Notify observers of extensions re-added after a pref change

chrome/browser/extensions/extension_toolbar_model_unittest.cc

 // Copyright 2014 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.
 
 #include "base/files/file_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/extensions/api/extension_action/extension_action_api.h"
@@ skipping 1293 matching lines @@
       SetReady();
   // Run tasks posted to TestExtensionSystem.
   base::RunLoop().RunUntilIdle();
 
   // We should still have no insertions, but should have an initialized count.
   EXPECT_TRUE(toolbar_model->extensions_initialized());
   EXPECT_EQ(0u, model_observer.inserted_count());
   EXPECT_EQ(1u, model_observer.initialized_count());
 }
 
+// Check that the toolbar model correctly clears and reorders when it detects
+// a preference change.
+TEST_F(ExtensionToolbarModelUnitTest, ToolbarModelPrefChange) {
+  Init();
+
+  ASSERT_TRUE(AddBrowserActionExtensions());
+
+  // We should start in the basic A B C order.
+  ASSERT_TRUE(browser_action_a());
+  EXPECT_EQ(browser_action_a(), GetExtensionAtIndex(0));
+  EXPECT_EQ(browser_action_b(), GetExtensionAtIndex(1));
+  EXPECT_EQ(browser_action_c(), GetExtensionAtIndex(2));
+  // Record the difference between the inserted and removed counts. The actual
+  // value of the counts is not important, but we need to be sure that if we
+  // call to remove any, we also add them back.
+  size_t inserted_and_removed_difference =
+      observer()->inserted_count() - observer()->removed_count();
+
+  // Assign a new order, B C A, and write it in the prefs.
+  ExtensionIdList new_order;
+  new_order.push_back(browser_action_b()->id());
+  new_order.push_back(browser_action_c()->id());
+  new_order.push_back(browser_action_a()->id());
+  ExtensionPrefs::Get(profile())->SetToolbarOrder(new_order);
+
+  // Ensure everything has time to run.
+  base::RunLoop().RunUntilIdle();
+
+  // The new order should be reflected in the model.
+  EXPECT_EQ(browser_action_b(), GetExtensionAtIndex(0));
+  EXPECT_EQ(browser_action_c(), GetExtensionAtIndex(1));
+  EXPECT_EQ(browser_action_a(), GetExtensionAtIndex(2));
+  EXPECT_EQ(inserted_and_removed_difference,
+            observer()->inserted_count() - observer()->removed_count());
+}
+
 }  // namespace extensions