GestureLongPress should be able to invoke BUBBLE_MODE_FAST_USER_SWITCH.

chrome/browser/ui/views/profiles/new_avatar_button.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_PROFILES_NEW_AVATAR_BUTTON_H_
 #define CHROME_BROWSER_UI_VIEWS_PROFILES_NEW_AVATAR_BUTTON_H_
 
 #include "chrome/browser/profiles/profile_info_cache_observer.h"
 #include "components/signin/core/browser/signin_error_controller.h"
 #include "ui/views/controls/button/label_button.h"
@@ skipping 13 matching lines @@
 
   NewAvatarButton(views::ButtonListener* listener,
                   AvatarButtonStyle button_style,
                   Browser* browser);
   ~NewAvatarButton() override;
 
   // Views::LabelButton
   bool OnMousePressed(const ui::MouseEvent& event) override;
   void OnMouseReleased(const ui::MouseEvent& event) override;
 
+  // Views
+  void OnGestureEvent(ui::GestureEvent* event) override;
+
  private:
   friend class ProfileChooserViewExtensionsTest;
 
   // ProfileInfoCacheObserver:
   void OnProfileAdded(const base::FilePath& profile_path) override;
   void OnProfileWasRemoved(const base::FilePath& profile_path,
                            const base::string16& profile_name) override;
   void OnProfileNameChanged(const base::FilePath& profile_path,
                             const base::string16& old_profile_name) override;
   void OnProfileSupervisedUserIdChanged(
@@ skipping 18 matching lines @@
 
   // This is used to check if the bubble was showing during the mouse pressed
   // event. If this is true then the mouse released event is ignored to prevent
   // the bubble from reshowing.
   bool suppress_mouse_released_action_;
 
   DISALLOW_COPY_AND_ASSIGN(NewAvatarButton);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PROFILES_NEW_AVATAR_BUTTON_H_