Set status tray height to 37px on login screen

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 fc38217098c7f02d724500cff2a746746302b1fe..41d5dbbedaa502c15709564ac9bf43018a9319a2 100644
--- a/ash/common/system/tray/tray_background_view.h
+++ b/ash/common/system/tray/tray_background_view.h
@@ -43,7 +43,7 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
 
     void set_size(const gfx::Size& size) { size_ = size; }
 
-    void SetMargin(const gfx::Insets& margin);
+    void SetMargin(int main_axis_margin, int cross_axis_margin);
 
     // views::View:
     gfx::Size GetPreferredSize() const override;
@@ -60,7 +60,8 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
 
     ShelfAlignment alignment_;
     gfx::Size size_;
-    gfx::Insets margin_;
+    int main_axis_margin_ = 0;
+    int cross_axis_margin_ = 0;
 
     DISALLOW_COPY_AND_ASSIGN(TrayContainer);
   };