FIX: Avoid cases on Android where keys can get stuck set as pressed (ISXB-475). (#1896)

Author: graham-huws

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -11,6 +11,7 @@ however, it has to be formatted properly to pass verification tests.
 ## [Unreleased] - YYYY-MM-DD
 
 ### Fixed
+- Physical keyboards used on Android/ChromeOS could have keys "stuck" reporting as pressed after a long press and release [ISXB-475](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-475).
 - NullReferenceException thrown when right-clicking an empty Action Map list in Input Actions Editor windows [ISXB-833](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-833).
 
 ## [1.8.1] - 2024-03-14

Packages/com.unity.inputsystem/InputSystem/InputManager.cs

@@ -3343,6 +3343,14 @@ private unsafe void OnUpdate(InputUpdateType updateType, ref InputEventBuffer ev
                             {
 #if UNITY_EDITOR
                                 m_Diagnostics?.OnEventTimestampOutdated(new InputEventPtr(currentEventReadPtr), device);
+#elif UNITY_ANDROID
+                                // Android keyboards can send events out of order: Holding down a key will send multiple
+                                // presses after a short time, like on most platforms. Unfortunately, on Android, the
+                                // last of these "presses" can be timestamped to be after the event of the key release.
+                                // If that happens, we'd skip the keyUp here, and the device state will have the key
+                                // "stuck" pressed. So, special case here to not skip keyboard events on Android. ISXB-475
+                                // N.B. Android seems to have similar issues with touch input (OnStateEvent, Touchscreen.cs)
+                                if (!(device is Keyboard))
 #endif
                                 break;
                             }