Fix shelf layout when switching from left-aligned shelf to right-aligned shelf

ash/common/system/tray/tray_background_view.cc

Index: ash/common/system/tray/tray_background_view.cc
diff --git a/ash/common/system/tray/tray_background_view.cc b/ash/common/system/tray/tray_background_view.cc
index 2192034abaa42599a181c45050136a256754490b..740dacacf67ab4645da8adc0b450788c3cfdf91f 100644
--- a/ash/common/system/tray/tray_background_view.cc
+++ b/ash/common/system/tray/tray_background_view.cc
@@ -251,8 +251,9 @@ TrayBackgroundView::~TrayBackgroundView() {
   StopObservingImplicitAnimations();
 }
 
-void TrayBackgroundView::Initialize() {
+void TrayBackgroundView::Initialize(const gfx::Insets& insets) {
   GetWidget()->AddObserver(widget_observer_.get());
+  SetTrayBorder(insets);
 }
 
 // static
@@ -375,11 +376,18 @@ void TrayBackgroundView::SetContentsBackground() {
   tray_container_->set_background(background_);
 }
 
-void TrayBackgroundView::SetShelfAlignment(ShelfAlignment alignment) {
+void TrayBackgroundView::SetShelfAlignment(ShelfAlignment alignment,
+                                           const gfx::Insets& insets) {
   shelf_alignment_ = alignment;
+  SetTrayBorder(insets);
   tray_container_->SetAlignment(alignment);
 }
 
+void TrayBackgroundView::SetTrayBorder(const gfx::Insets& insets) {
+  SetBorder(views::Border::CreateEmptyBorder(insets.top(), insets.left(),
+                                             insets.bottom(), insets.right()));
+}
+
 void TrayBackgroundView::OnImplicitAnimationsCompleted() {
   // If there is another animation in the queue, the reverse animation was
   // triggered before the completion of animating to invisible. Do not turn off