Widget opacity goes from 0 to 1, not 0 to 255.

ash/system/user/user_view.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 "ash/system/user/user_view.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "ash/multi_profile_uma.h"
@@ skipping 415 matching lines @@
   // gets destroyed..
   add_menu_option_.reset(new views::Widget);
   views::Widget::InitParams params;
   params.type = views::Widget::InitParams::TYPE_TOOLTIP;
   params.keep_on_top = true;
   params.context = this->GetWidget()->GetNativeWindow();
   params.accept_events = true;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
   params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
   add_menu_option_->Init(params);
-  add_menu_option_->SetOpacity(0xFF);
+  add_menu_option_->SetOpacity(1.f);
   add_menu_option_->GetNativeWindow()->set_owned_by_parent(false);
   SetShadowType(add_menu_option_->GetNativeView(), ::wm::SHADOW_TYPE_NONE);
 
   // Position it below our user card.
   gfx::Rect bounds = user_card_view_->GetBoundsInScreen();
   bounds.set_y(bounds.y() + bounds.height());
   add_menu_option_->SetBounds(bounds);
 
   // Show the content.
   add_menu_option_->SetAlwaysOnTop(true);
@@ skipping 70 matching lines @@
   focus_manager_ = NULL;
   if (user_card_view_->GetFocusManager())
     user_card_view_->GetFocusManager()->ClearFocus();
   popup_message_.reset();
   mouse_watcher_.reset();
   add_menu_option_.reset();
 }
 
 }  // namespace tray
 }  // namespace ash