Fix stylus tools palette.

ash/system/palette/palette_utils.cc

Index: ash/system/palette/palette_utils.cc
diff --git a/ash/system/palette/palette_utils.cc b/ash/system/palette/palette_utils.cc
index 7181d6c5addf6bcfab86b78c472dfc6c2475d078..97338a90047c8ba24463bfec64e44b018f9778d8 100644
--- a/ash/system/palette/palette_utils.cc
+++ b/ash/system/palette/palette_utils.cc
@@ -5,12 +5,16 @@
 #include "ash/system/palette/palette_utils.h"
 
 #include "ash/ash_switches.h"
+#include "ash/palette_delegate.h"
+#include "ash/public/cpp/config.h"
 #include "ash/shelf/wm_shelf.h"
+#include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/system/palette/palette_tray.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/wm_window.h"
 #include "base/command_line.h"
+#include "ui/display/display.h"
 #include "ui/events/devices/input_device_manager.h"
 #include "ui/events/devices/touchscreen_device.h"
 #include "ui/gfx/geometry/point.h"
@@ -22,11 +26,13 @@ bool HasStylusInput() {
   // Allow the user to force enable or disable by passing a switch. If both are
   // present, enabling takes precedence over disabling.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kAshForceEnablePalette)) {
+          switches::kAshForceEnableStylusTools)) {
     return true;
   }
 
-  // Check to see if the hardware reports it is stylus capable.
+  // Returns true if the hardware reports it is stylus capable. This
+  // will return false even if there is a stylus input device until hardware
+  // probing is complete (see ui::InputDeviceEventObserver).
   for (const ui::TouchscreenDevice& device :
        ui::InputDeviceManager::GetInstance()->GetTouchscreenDevices()) {
     if (device.is_stylus &&
@@ -43,6 +49,14 @@ bool IsPaletteEnabledOnEveryDisplay() {
       switches::kAshEnablePaletteOnAllDisplays);
 }
 
+bool ShouldShowPalette() {
+  return HasStylusInput() &&
+         (display::Display::HasInternalDisplay() ||
+          IsPaletteEnabledOnEveryDisplay()) &&
+         Shell::Get()->palette_delegate() &&
+         Shell::Get()->palette_delegate()->ShouldShowPalette();
+}
+
 bool PaletteContainsPointInScreen(const gfx::Point& point) {
   for (WmWindow* window : ShellPort::Get()->GetAllRootWindows()) {
     PaletteTray* palette_tray =