cros/ash: Only show the stylus palette on the internal display.

ash/common/system/status_area_widget.cc

Index: ash/common/system/status_area_widget.cc
diff --git a/ash/common/system/status_area_widget.cc b/ash/common/system/status_area_widget.cc
index cf5ae68e1a7ff2b35187053b56b02bf069553dae..0dcd8f9f5a68575dc1535c2bdbe34fece19a26bd 100644
--- a/ash/common/system/status_area_widget.cc
+++ b/ash/common/system/status_area_widget.cc
@@ -25,6 +25,8 @@
 #include "ash/common/system/chromeos/palette/palette_utils.h"
 #include "ash/common/system/chromeos/session/logout_button_tray.h"
 #include "ash/common/system/chromeos/virtual_keyboard/virtual_keyboard_tray.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
 #endif
 
 namespace ash {
@@ -251,7 +253,16 @@ void StatusAreaWidget::AddLogoutButtonTray() {
 }
 
 void StatusAreaWidget::AddPaletteTray() {
-  if (IsPaletteFeatureEnabled()) {
+  if (!IsPaletteFeatureEnabled())
+    return;
+
+  const display::Display& display =
+      display::Screen::GetScreen()->GetDisplayNearestWindow(GetNativeWindow());

[James Cook, 2016/09/01 17:00:55]

Use WmLookup::Get()->GetWindowForWidget(this)->GetDisplayNearestWindow()
instead. (You'd have no way of knowing this, but I suspect what you have
wouldn't work on mustash since GetNativeWidget() returns aura::Window.)

[jdufault, 2016/09/02 20:12:37]

Done.

+
+  // Create the palette only on the internal display, where the stylus is
+  // available. We also create a palette on every display if requested from the
+  // command line.
+  if (display.IsInternal() || IsPaletteEnabledOnEveryDisplay()) {
     palette_tray_ = new PaletteTray(wm_shelf_);
     status_area_widget_delegate_->AddTray(palette_tray_);
   }