xrt: Add xrt_android header with info about Android lifecycle callbacks

Co-authored-By: Jarvis Huang <quic_jarvhuan@quicinc.com>
Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/1655>

doc/changes/xrt/mr.1655.md

@@ -1 +1,2 @@
 - Move `xrt_instance_info` members to nested `xrt_application_info` struct, and add a parallel `xrt_platform_info`.
+- Add `xrt/xrt_android.h` header.

src/xrt/include/xrt/xrt_android.h

@@ -0,0 +1,52 @@
+// Copyright 2021-2024, Collabora, Ltd.
+// SPDX-License-Identifier: BSL-1.0
+/*!
+ * @file
+ * @brief  Header holding Android-specific details.
+ * @author Rylie Pavlik <rylie.pavlik@collabora.com>
+ * @ingroup xrt_iface
+ */
+
+#pragma once
+
+#include "xrt/xrt_config_os.h"
+#include "xrt/xrt_compiler.h"
+#include "xrt/xrt_results.h"
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct _JavaVM;
+struct xrt_instance_android;
+struct xrt_instance_info;
+
+/*!
+ * Distinguishes the possible Android lifecycle events from each other.
+ *
+ * Used as a bitmask when registering for callbacks.
+ */
+enum xrt_android_lifecycle_event
+{
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_CREATE = 1 << 0,
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_DESTROY = 1 << 1,
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_PAUSE = 1 << 2,
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_RESUME = 1 << 3,
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_START = 1 << 4,
+	XRT_ANDROID_LIVECYCLE_EVENT_ON_STOP = 1 << 5,
+};
+
+/*!
+ * A callback type for a handler of Android lifecycle events.
+ *
+ * Return true to be removed from the callback list.
+ */
+typedef bool (*xrt_android_lifecycle_event_handler_t)(struct xrt_instance_android *xinst_android,
+                                                      enum xrt_android_lifecycle_event event,
+                                                      void *userdata);
+
+#ifdef __cplusplus
+}
+#endif