Prepare status area to support multiple trays.

ash/system/tray/tray_background_view.cc

 // Copyright (c) 2012 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/system/tray/tray_background_view.h"
 
 #include "ash/launcher/background_animator.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 36 matching lines @@
 
   int alpha_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayBackground);
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 // TrayBackgroundView
 
 TrayBackgroundView::TrayBackgroundView()
-    : background_(NULL),
-    ALLOW_THIS_IN_INITIALIZER_LIST(hide_background_animator_(
-        this, 0, kTrayBackgroundAlpha)),
-    ALLOW_THIS_IN_INITIALIZER_LIST(hover_background_animator_(
-        this, 0, kTrayBackgroundHoverAlpha - kTrayBackgroundAlpha)) {
+    : shelf_alignment_(SHELF_ALIGNMENT_BOTTOM),
+      background_(NULL),
+      ALLOW_THIS_IN_INITIALIZER_LIST(hide_background_animator_(
+          this, 0, kTrayBackgroundAlpha)),
+      ALLOW_THIS_IN_INITIALIZER_LIST(hover_background_animator_(
+          this, 0, kTrayBackgroundHoverAlpha - kTrayBackgroundAlpha)) {
   set_border(views::Border::CreateEmptyBorder(0, 0,
         kPaddingFromBottomOfScreenBottomAlignment,
         kPaddingFromRightEdgeOfScreenBottomAlignment));
   set_notify_enter_exit_on_child(true);
 
   // Initially we want to paint the background, but without the hover effect.
   SetPaintsBackground(true, internal::BackgroundAnimator::CHANGE_IMMEDIATE);
   hover_background_animator_.SetPaintsBackground(false,
       internal::BackgroundAnimator::CHANGE_IMMEDIATE);
 }
@@ skipping 30 matching lines @@
   SetLayoutManager(new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0));
   AddChildView(contents);
 }
 
 void TrayBackgroundView::SetPaintsBackground(
       bool value,
       internal::BackgroundAnimator::ChangeType change_type) {
   hide_background_animator_.SetPaintsBackground(value, change_type);
 }
 
+void TrayBackgroundView::SetShelfAlignment(ShelfAlignment alignment) {
+  shelf_alignment_ = alignment;
+}
+
 }  // namespace internal
 }  // namespace ash