Make LogoutButtonTray a regular View

ash/system/tray/system_tray.h

Index: ash/system/tray/system_tray.h
diff --git a/ash/system/tray/system_tray.h b/ash/system/tray/system_tray.h
index e54d30db3c63b368bd7899c45a9662a17471f69d..603997a78891fd1bb964c676a06b29eff90a6ef7 100644
--- a/ash/system/tray/system_tray.h
+++ b/ash/system/tray/system_tray.h
@@ -86,7 +86,7 @@ class ASH_EXPORT SystemTray : public TrayBackgroundView,
   void UpdateAfterLoginStatusChange(LoginStatus login_status);
 
   // Updates the items when the shelf alignment changes.
-  void UpdateAfterShelfAlignmentChange(ShelfAlignment alignment);
+  void UpdateItemsAfterShelfAlignmentChange();
 
   // Returns true if the shelf should be forced visible when auto-hidden.
   bool ShouldShowShelf() const;
@@ -115,7 +115,7 @@ class ASH_EXPORT SystemTray : public TrayBackgroundView,
   TrayAudio* GetTrayAudio() const;
 
   // Overridden from TrayBackgroundView.
-  void SetShelfAlignment(ShelfAlignment alignment) override;
+  void UpdateAfterShelfAlignmentChange() override;
   void AnchorUpdated() override;
   base::string16 GetAccessibleNameForTray() override;
   void BubbleResized(const views::TrayBubbleView* bubble_view) override;