android: route asymmetric companion displays

tests/engine/android_asymmetric_display.lua

@@ -0,0 +1,35 @@
+local function read(path)
+  local file = assert(io.open(path, "rb"))
+  local source = file:read("*a")
+  file:close()
+  return source
+end
+
+local function check(value, message)
+  if not value then error(message, 2) end
+end
+
+local java = read(
+  "mobile/android/love/src/main/java/org/love2d/android/GameActivity.java")
+local manifest = read("mobile/android/app/src/main/AndroidManifest.xml")
+
+check(manifest:find("android.allow_multiple_resumed_activities", 1, true)
+    and manifest:find("GameActivity$SecondaryActivity", 1, true)
+    and manifest:find('android:exported="false"', 1, true),
+  "the private companion Activity opts into Android multi-display resume")
+check(java:find("android.os.Build.VERSION.SDK_INT < 29", 1, true)
+    and java:find("options.setLaunchDisplayId", 1, true),
+  "the primary-display fallback is restricted to Android 10+")
+check(java:find("SECONDARY_TARGET_HANDHELD", 1, true)
+    and java:find("SECONDARY_TARGET_EXTERNAL", 1, true)
+    and java:find("handheldAvailable ? handheld : external", 1, true),
+  "routing hints retain a safe available-display fallback")
+check(java:find("dualScreenDisplayMode != %-1")
+    and java:find("AYN_SECOND_SCREEN", 1, true)
+    and java:find("dualScreenModeObserverRegistered", 1, true),
+  "the optional AYN state is guarded and lifecycle-bound")
+check(java:find("activity.dispatchKeyEvent", 1, true)
+    and java:find("activity.dispatchGenericMotionEvent", 1, true),
+  "companion windows forward controller input to the game Activity")
+
+print("android asymmetric display routing: ok")