[Chrome OS MD] Draw a 1px separator between 2 tray items

ash/common/system/overview/overview_button_tray.cc

Index: ash/common/system/overview/overview_button_tray.cc
diff --git a/ash/common/system/overview/overview_button_tray.cc b/ash/common/system/overview/overview_button_tray.cc
index e3508b474c4a26553b89336f0d3ed517b8783ff8..38bfd8edcf7738e0b9058a38e10fa1e9aba6aaa5 100644
--- a/ash/common/system/overview/overview_button_tray.cc
+++ b/ash/common/system/overview/overview_button_tray.cc
@@ -33,6 +33,10 @@ const int kHorizontalShelfVerticalPadding = 4;
 const int kVerticalShelfHorizontalPadding = 2;
 const int kVerticalShelfVerticalPadding = 5;
 
+// Padding used to adjust the user-visible size of overview tray's dark
+// background.
+const int kBackgroundTrayPadding = 3;
+
 }  // namespace
 
 namespace ash {
@@ -40,6 +44,7 @@ namespace ash {
 OverviewButtonTray::OverviewButtonTray(WmShelf* wm_shelf)
     : TrayBackgroundView(wm_shelf), icon_(nullptr) {
   SetContentsBackground();
+  SetOverviewTrayBorder();
 
   icon_ = new views::ImageView();
   if (MaterialDesignController::IsShelfMaterial()) {
@@ -110,7 +115,10 @@ void OverviewButtonTray::SetShelfAlignment(ShelfAlignment alignment) {
     return;
 
   TrayBackgroundView::SetShelfAlignment(alignment);
-  SetIconBorderForShelfAlignment();
+  if (!ash::MaterialDesignController::IsShelfMaterial()) {
+    SetOverviewTrayBorder();
+    SetIconBorderForShelfAlignment();
+  }
 }
 
 void OverviewButtonTray::SetIconBorderForShelfAlignment() {
@@ -123,17 +131,22 @@ void OverviewButtonTray::SetIconBorderForShelfAlignment() {
         gfx::Insets(vertical_padding, horizontal_padding)));
   } else {
     if (IsHorizontalAlignment(shelf_alignment())) {
-      icon_->SetBorder(views::Border::CreateEmptyBorder(
-          kHorizontalShelfVerticalPadding, kHorizontalShelfHorizontalPadding,
-          kHorizontalShelfVerticalPadding, kHorizontalShelfHorizontalPadding));
+      icon_->SetBorder(views::Border::CreateEmptyBorder(gfx::Insets(
+          kHorizontalShelfVerticalPadding, kHorizontalShelfHorizontalPadding)));
     } else {
-      icon_->SetBorder(views::Border::CreateEmptyBorder(
-          kVerticalShelfVerticalPadding, kVerticalShelfHorizontalPadding,
-          kVerticalShelfVerticalPadding, kVerticalShelfHorizontalPadding));
+      icon_->SetBorder(views::Border::CreateEmptyBorder(gfx::Insets(
+          kVerticalShelfVerticalPadding, kVerticalShelfHorizontalPadding)));
     }
   }
 }
 
+void OverviewButtonTray::SetOverviewTrayBorder() {
+  if (!ash::MaterialDesignController::IsShelfMaterial()) {
+    tray_container()->SetBorder(
+        views::Border::CreateEmptyBorder(gfx::Insets(kBackgroundTrayPadding)));
+  }
+}
+
 void OverviewButtonTray::UpdateIconVisibility() {
   // The visibility of the OverviewButtonTray has diverge from
   // WindowSelectorController::CanSelect. The visibility of the button should
@@ -142,7 +155,6 @@ void OverviewButtonTray::UpdateIconVisibility() {
   WmShell* shell = WmShell::Get();
   SessionStateDelegate* session_state_delegate =
       shell->GetSessionStateDelegate();
-
   SetVisible(
       shell->maximize_mode_controller()->IsMaximizeModeWindowManagerEnabled() &&
       session_state_delegate->IsActiveUserSessionStarted() &&