Auto open and close the palette on an eject event.

ash/common/system/chromeos/palette/palette_tray.cc

Index: ash/common/system/chromeos/palette/palette_tray.cc
diff --git a/ash/common/system/chromeos/palette/palette_tray.cc b/ash/common/system/chromeos/palette/palette_tray.cc
index 1a13c9c4ba9ffe9af7800b322415cdbfa9d066d7..a485f171ee8b5811481f45b364c574b1290033f9 100644
--- a/ash/common/system/chromeos/palette/palette_tray.cc
+++ b/ash/common/system/chromeos/palette/palette_tray.cc
@@ -4,6 +4,7 @@
 
 #include "ash/common/system/chromeos/palette/palette_tray.h"
 
+#include "ash/common/palette_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shelf/wm_shelf_util.h"
@@ -22,6 +23,7 @@
 #include "grit/ash_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
+#include "ui/events/devices/stylus_state.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/label.h"
@@ -134,6 +136,10 @@ PaletteTray::PaletteTray(WmShelf* wm_shelf)
 
   WmShell::Get()->AddShellObserver(this);
   WmShell::Get()->GetSessionStateDelegate()->AddSessionStateObserver(this);
+  if (WmShell::Get()->palette_delegate()) {
+    WmShell::Get()->palette_delegate()->SetStylusStateChangedCallback(
+        base::Bind(&PaletteTray::OnStylusStateChanged, base::Unretained(this)));

[stevenjb, 2016/08/25 22:48:56]

Need to pass this as a weak_ptr. It's always iffy to rely on destruction order
and with views it is especially uncertain.

[jdufault, 2016/08/25 23:09:15]

Done.

+  }
 
   UpdateIconVisibility();
 }
@@ -210,7 +216,7 @@ void PaletteTray::SessionStateChanged(
 }
 
 void PaletteTray::ClickedOutsideBubble() {
-  HidePalette();
+  bubble_.reset();
 }
 
 base::string16 PaletteTray::GetAccessibleNameForTray() {
@@ -315,6 +321,16 @@ void PaletteTray::UpdateTrayIcon() {
   icon_->SetImage(CreateVectorIcon(icon, kShelfIconSize, kShelfIconColor));
 }
 
+void PaletteTray::OnStylusStateChanged(ui::StylusState stylus_state) {
+  if (!WmShell::Get()->palette_delegate()->ShouldAutoOpenPalette())
+    return;
+
+  if (stylus_state == ui::StylusState::REMOVED && !bubble_)
+    OpenBubble();
+  else if (stylus_state == ui::StylusState::INSERTED && bubble_)
+    bubble_.reset();
+}
+
 void PaletteTray::UpdateIconVisibility() {
   if (!IsPaletteEnabled())
     return;