[Android] Fork a detached child process from adb_logcat_monitor.py.

build/android/adb_logcat_monitor.py

Index: build/android/adb_logcat_monitor.py
diff --git a/build/android/adb_logcat_monitor.py b/build/android/adb_logcat_monitor.py
index 35ef7905b24fcb9a30506f5e0d246d3f52085214..0464b5303c1e04a422785260faf77553dd77fa9f 100755
--- a/build/android/adb_logcat_monitor.py
+++ b/build/android/adb_logcat_monitor.py
@@ -96,6 +96,15 @@ def GetAttachedDevices(adb_cmd):
 
 def main(base_dir, adb_cmd='adb'):
   """Monitor adb forever.  Expects a SIGINT (Ctrl-C) to kill."""
+  # Spawn a detached child process.
+  pid = os.fork()
+  if pid > 0:
+    os._exit(os.EX_OK)
+  elif pid < 0:
+    sys.exit('Unable to spawn a detached child process.')
+  os.setsid()
+  # The rest happens in the child process.
+
   # We create the directory to ensure 'run once' semantics
   if os.path.exists(base_dir):
     print 'adb_logcat_monitor: %s already exists? Cleaning' % base_dir