Remove the extra separator appears on the right side of the shelf

ash/common/system/chromeos/session/logout_button_tray.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/common/system/chromeos/session/logout_button_tray.h"
 
 #include <memory>
 #include <utility>
 
 #include "ash/common/material_design/material_design_controller.h"
@@ skipping 98 matching lines @@
   if (MaterialDesignController::IsShelfMaterial()) {
     views::MdTextButton* button =
         views::MdTextButton::Create(this, base::string16());
     button->SetProminent(true);
     button->SetBgColorOverride(gfx::kGoogleRed700);
     // Base font size + 2 = 14.
     // TODO(estade): should this 2 be shared with other tray views? See
     // crbug.com/623987
     button->AdjustFontSize(2);
     button_ = button;
+    SetSeparatorVisibility(false);

[James Cook, 2017/01/09 23:50:53]

nit: comment why this is false (because logout button has a strong visual right
edge so doesn't need it?)

[yiyix, 2017/01/10 01:02:53]

You are right, after removing the entire logics on whether to show a separator,
some comments would help the readers to understand the new logic.

   } else {
     button_ = new LogoutButton(this);
   }
   tray_container()->AddChildView(button_);
   if (!MaterialDesignController::IsShelfMaterial())
     tray_container()->SetBorder(views::NullBorder());
   WmShell::Get()->system_tray_notifier()->AddLogoutButtonObserver(this);
 }
 
 LogoutButtonTray::~LogoutButtonTray() {
@@ skipping 70 matching lines @@
     button_->SetAccessibleName(title);
     button_->SetImage(
         views::LabelButton::STATE_NORMAL,
         gfx::CreateVectorIcon(gfx::VectorIconId::SHELF_LOGOUT, kTrayIconColor));
     button_->SetMinSize(gfx::Size(button_size, button_size));
   }
   UpdateVisibility();
 }
 
 }  // namespace ash