[Extensions] Observe unloading extensions in the TabHelper

chrome/browser/extensions/tab_helper_unittest.cc

+// Copyright 2016 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 "chrome/browser/extensions/tab_helper.h"
+
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_service_test_with_install.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/test/web_contents_tester.h"
+
+namespace extensions {
+
+TEST_F(ExtensionServiceTestWithInstall, TabHelperClearsExtensionOnUnload) {
+  InitializeEmptyExtensionService();
+  const Extension* extension =
+      PackAndInstallCRX(data_dir().AppendASCII("hosted_app"), INSTALL_NEW);
+  ASSERT_TRUE(extension);
+  std::unique_ptr<content::WebContents> web_contents(
+      content::WebContentsTester::CreateTestWebContents(profile(), nullptr));
+  TabHelper::CreateForWebContents(web_contents.get());
+  TabHelper* tab_helper = TabHelper::FromWebContents(web_contents.get());
+  tab_helper->SetExtensionApp(extension);
+  EXPECT_EQ(extension, tab_helper->extension_app());
+  EXPECT_TRUE(tab_helper->is_app());
+  service()->UnloadExtension(extension->id(),
+                             UnloadedExtensionInfo::REASON_UNDEFINED);
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(nullptr, tab_helper->extension_app());
+}
+
+}  // namespace extensions