New post-sideload UI:

chrome/browser/extensions/extension_browsertest.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_BROWSERTEST_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_BROWSERTEST_H_
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/scoped_temp_dir.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/features/feature.h"
+#include "chrome/common/extensions/feature_switch.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/web_contents.h"
 
 // Base class for extension browser tests. Provides utilities for loading,
 // unloading, and installing extensions.
 class ExtensionBrowserTest : virtual public InProcessBrowserTest,
                              public content::NotificationObserver {
@@ skipping 215 matching lines @@
   // When waiting for page action count to change, we wait until it reaches this
   // value.
   int target_page_action_count_;
 
   // When waiting for visible page action count to change, we wait until it
   // reaches this value.
   int target_visible_page_action_count_;
 
   // Make the current channel "dev" for the duration of the test.
   extensions::Feature::ScopedCurrentChannel current_channel_;
+
+  // Disable external install UI.
+  extensions::FeatureSwitch::ScopedOverride
+      override_prompt_for_external_extensions_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_BROWSERTEST_H_