Merge "Handle cached bluetooth device with stylus pref" into main

src/com/android/settings/connecteddevice/stylus/StylusDevicesController.java

@@ -108,10 +108,15 @@ public class StylusDevicesController extends AbstractPreferenceController implem
             return null;
         }
 
-        boolean doesStylusSupportTailButton = mInputDevice.hasKeys(
-                KeyEvent.KEYCODE_STYLUS_BUTTON_TAIL)[0];
-        if (!doesStylusSupportTailButton) {
-            return null;
+        // Check if the connected stylus supports the tail button. A connected device is when input
+        // device is available (mInputDevice != null). For a cached device (mInputDevice == null)
+        // there isn't way to check if the device supports the button so assume it does.
+        if (mInputDevice != null) {
+            boolean doesStylusSupportTailButton =
+                    mInputDevice.hasKeys(KeyEvent.KEYCODE_STYLUS_BUTTON_TAIL)[0];
+            if (!doesStylusSupportTailButton) {
+                return null;
+            }
         }
 
         Preference pref = preference == null ? new Preference(mContext) : preference;