Make LogoutButtonTray a regular View

ash/system/overview/overview_button_tray.h

Index: ash/system/overview/overview_button_tray.h
diff --git a/ash/system/overview/overview_button_tray.h b/ash/system/overview/overview_button_tray.h
index 5b82d4dea09b0b6ef8f164a8787c904bb93f2e63..74a6794c66494d51b2f67f94f4ad28ac42e6e55b 100644
--- a/ash/system/overview/overview_button_tray.h
+++ b/ash/system/overview/overview_button_tray.h
@@ -49,15 +49,10 @@ class ASH_EXPORT OverviewButtonTray : public TrayBackgroundView,
   void ClickedOutsideBubble() override;
   base::string16 GetAccessibleNameForTray() override;
   void HideBubbleWithView(const views::TrayBubbleView* bubble_view) override;
-  void SetShelfAlignment(ShelfAlignment alignment) override;
 
  private:
   friend class OverviewButtonTrayTest;
 
-  // Creates a new border for the icon. The padding is determined based on the
-  // alignment of the shelf.
-  void SetIconBorderForShelfAlignment();
-
   // Sets the icon to visible if maximize mode is enabled and
   // WindowSelectorController::CanSelect.
   void UpdateIconVisibility();