[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..801aaf411c6013998409d6bec2ed2e45f43eed9b 100644
--- a/ash/common/system/overview/overview_button_tray.cc
+++ b/ash/common/system/overview/overview_button_tray.cc
@@ -33,6 +33,9 @@ const int kHorizontalShelfVerticalPadding = 4;
 const int kVerticalShelfHorizontalPadding = 2;
 const int kVerticalShelfVerticalPadding = 5;
 
+// Padding used to adjust the user-visible size of overview dark background.

[varkha, 2016/07/14 21:34:47]

nit: s/overview/overview tray

[yiyix, 2016/07/26 20:27:30]

Done.

+const int kBackgroundTrayPadding = 3;
+
 }  // namespace
 
 namespace ash {
@@ -40,6 +43,7 @@ namespace ash {
 OverviewButtonTray::OverviewButtonTray(WmShelf* wm_shelf)
     : TrayBackgroundView(wm_shelf), icon_(nullptr) {
   SetContentsBackground();
+  AdjustOverviewBackground();
 
   icon_ = new views::ImageView();
   if (MaterialDesignController::IsShelfMaterial()) {
@@ -110,6 +114,7 @@ void OverviewButtonTray::SetShelfAlignment(ShelfAlignment alignment) {
     return;
 
   TrayBackgroundView::SetShelfAlignment(alignment);
+  AdjustOverviewBackground();

[varkha, 2016/07/14 21:34:47]

Do you need to call those 2 methods that create borders here in MD case given
that the padding is not dependent on |alignment|?

[yiyix, 2016/07/26 20:27:30]

true, I will add a condition. thanks

   SetIconBorderForShelfAlignment();
 }
 
@@ -134,6 +139,14 @@ void OverviewButtonTray::SetIconBorderForShelfAlignment() {
   }
 }
 
+void OverviewButtonTray::AdjustOverviewBackground() {
+  if (!ash::MaterialDesignController::IsShelfMaterial()) {
+    tray_container()->SetBorder(views::Border::CreateEmptyBorder(

[varkha, 2016/07/14 21:34:47]

nit: simpler to use gfx::Insets(kBackgroundTrayPadding).
Bonus points for fixing that elsewhere in this file (there is a Insets ctor that
takes just 2 values so no need to repeat all 4).

[yiyix, 2016/07/26 20:27:30]

Done.

+        kBackgroundTrayPadding, kBackgroundTrayPadding, kBackgroundTrayPadding,
+        kBackgroundTrayPadding));
+  }
+}
+
 void OverviewButtonTray::UpdateIconVisibility() {
   // The visibility of the OverviewButtonTray has diverge from
   // WindowSelectorController::CanSelect. The visibility of the button should