Add a snapshot of flutter/engine/src/build to our sdk

build/android/host_heartbeat.py

+#!/usr/bin/env python
+#
+# Copyright (c) 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Sends a heart beat pulse to the currently online Android devices.
+This heart beat lets the devices know that they are connected to a host.
+"""
+# pylint: disable=W0702
+
+import sys
+import time
+
+from pylib.device import device_utils
+
+PULSE_PERIOD = 20
+
+def main():
+  while True:
+    try:
+      devices = device_utils.DeviceUtils.HealthyDevices()
+      for d in devices:
+        d.RunShellCommand(['touch', '/sdcard/host_heartbeat'],
+                          check_return=True)
+    except:
+      # Keep the heatbeat running bypassing all errors.
+      pass
+    time.sleep(PULSE_PERIOD)
+
+
+if __name__ == '__main__':
+  sys.exit(main())