Remove non-MD code from TrayBackgroundView

ash/common/system/tray/tray_background_view.h

Index: ash/common/system/tray/tray_background_view.h
diff --git a/ash/common/system/tray/tray_background_view.h b/ash/common/system/tray/tray_background_view.h
index 49e71055e55adee2fc1244a00d2b6f4ef0d96dff..3b66db3557b1396e58fa71528a35a1780ed3d32a 100644
--- a/ash/common/system/tray/tray_background_view.h
+++ b/ash/common/system/tray/tray_background_view.h
@@ -60,7 +60,7 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
     DISALLOW_COPY_AND_ASSIGN(TrayContainer);
   };
 
-  explicit TrayBackgroundView(WmShelf* wm_shelf);
+  TrayBackgroundView(WmShelf* wm_shelf, bool no_background);

[Evan Stade, 2017/03/02 02:49:51]

I would expect this to be inverted, i.e. bool draws_background

That said, does LogoutButton need to be a TrayBackgroundView? It doesn't have a
background or a separator. What functionality is it actually relying on?

[mohsen, 2017/03/02 04:07:09]

Done.
 
Hmm, good question. It doesn't even use clickability of ActionableView since it
hosts its own clickable button. It apparently only uses TrayBackgroundView's
TrayContainer layout. Probably we can take TrayContainer out of
TrayBackgroundView and make logout button a regular View that uses
TrayContainer? Added a TODO.

   ~TrayBackgroundView() override;
 
   // Called after the tray has been added to the widget containing it.
@@ -81,7 +81,6 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
   std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
   std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
       const override;
-  void OnGestureEvent(ui::GestureEvent* event) override;
 
   // Called whenever the shelf alignment changes.
   virtual void SetShelfAlignment(ShelfAlignment alignment);
@@ -103,14 +102,6 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
   // May close the bubble.
   virtual void ClickedOutsideBubble() = 0;
 
-  // Sets |contents| as a child.
-  void SetContents(views::View* contents);
-
-  // Creates and sets contents background to |background_|. |draws_active|
-  // determines if the view's background should be drawn as active when the view
-  // is in the active state.
-  void SetContentsBackground(bool draws_active);
-
   // Returns the bubble anchor alignment based on |shelf_alignment_|.
   views::TrayBubbleView::AnchorAlignment GetAnchorAlignment() const;
 
@@ -178,8 +169,8 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
   // Owned by the view passed to SetContents().
   TrayBackground* background_;
 
-  // Determines if the view is active. This changes how the background is drawn
-  // in non-MD version and how the ink drop ripples behave in MD version.
+  // Determines if the view is active. This changes how  the ink drop ripples
+  // behave.
   bool is_active_;
 
   // Visibility of this tray's separator which is a line of 1x32px and 4px to