cros: Move TrayBluetoothHelper out of chrome into ash

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 0cb30968a62a1df13a4d756e8e69e9136b51f88c..1470da3f9c7269e6b9b80cd3941cd5978f9f04da 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -206,6 +206,8 @@ component("ash") {
     "common/system/chromeos/bluetooth/bluetooth_observer.h",
     "common/system/chromeos/bluetooth/tray_bluetooth.cc",
     "common/system/chromeos/bluetooth/tray_bluetooth.h",
+    "common/system/chromeos/bluetooth/tray_bluetooth_helper.cc",
+    "common/system/chromeos/bluetooth/tray_bluetooth_helper.h",
     "common/system/chromeos/brightness/brightness_controller_chromeos.cc",
     "common/system/chromeos/brightness/brightness_controller_chromeos.h",
     "common/system/chromeos/brightness/tray_brightness.cc",
@@ -1165,6 +1167,7 @@ source_set("common_unittests") {
     "common/shelf/shelf_tooltip_manager_unittest.cc",
     "common/shelf/shelf_window_watcher_unittest.cc",
     "common/system/chromeos/audio/tray_audio_unittest.cc",
+    "common/system/chromeos/bluetooth/tray_bluetooth_helper_unittest.cc",
     "common/system/chromeos/brightness/tray_brightness_unittest.cc",
     "common/system/chromeos/ime_menu/ime_menu_tray_unittest.cc",
     "common/system/chromeos/media_security/multi_profile_media_tray_item_unittest.cc",