diff -r 000000000000 -r 6474c204b198 media/webrtc/trunk/build/android/adb_logcat_monitor.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/media/webrtc/trunk/build/android/adb_logcat_monitor.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,155 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2012 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.
+
+"""Saves logcats from all connected devices.
+
+Usage: adb_logcat_monitor.py <base_dir> [<adb_binary_path>]
+
+This script will repeatedly poll adb for new devices and save logcats
+inside the <base_dir> directory, which it attempts to create.  The
+script will run until killed by an external signal.  To test, run the
+script in a shell and <Ctrl>-C it after a while.  It should be
+resilient across phone disconnects and reconnects and start the logcat
+early enough to not miss anything.
+"""
+
+import logging
+import os
+import re
+import shutil
+import signal
+import subprocess
+import sys
+import time
+
+# Map from device_id -> (process, logcat_num)
+devices = {}
+
+
+class TimeoutException(Exception):
+  """Exception used to signal a timeout."""
+  pass
+
+
+class SigtermError(Exception):
+  """Exception used to catch a sigterm."""
+  pass
+
+
+def StartLogcatIfNecessary(device_id, adb_cmd, base_dir):
+  """Spawns a adb logcat process if one is not currently running."""
+  process, logcat_num = devices[device_id]
+  if process:
+    if process.poll() is None:
+      # Logcat process is still happily running
+      return
+    else:
+      logging.info('Logcat for device %s has died', device_id)
+      error_filter = re.compile('- waiting for device -')
+      for line in process.stderr:
+        if not error_filter.match(line):
+          logging.error(device_id + ':   ' + line)
+
+  logging.info('Starting logcat %d for device %s', logcat_num,
+               device_id)
+  logcat_filename = 'logcat_%s_%03d' % (device_id, logcat_num)
+  logcat_file = open(os.path.join(base_dir, logcat_filename), 'w')
+  process = subprocess.Popen([adb_cmd, '-s', device_id,
+                              'logcat', '-v', 'threadtime'],
+                             stdout=logcat_file,
+                             stderr=subprocess.PIPE)
+  devices[device_id] = (process, logcat_num + 1)
+
+
+def GetAttachedDevices(adb_cmd):
+  """Gets the device list from adb.
+
+  We use an alarm in this function to avoid deadlocking from an external
+  dependency.
+
+  Args:
+    adb_cmd: binary to run adb
+
+  Returns:
+    list of devices or an empty list on timeout
+  """
+  signal.alarm(2)
+  try:
+    out, err = subprocess.Popen([adb_cmd, 'devices'],
+                                stdout=subprocess.PIPE,
+                                stderr=subprocess.PIPE).communicate()
+    if err:
+      logging.warning('adb device error %s', err.strip())
+    return re.findall('^(\w+)\tdevice$', out, re.MULTILINE)
+  except TimeoutException:
+    logging.warning('"adb devices" command timed out')
+    return []
+  except (IOError, OSError):
+    logging.exception('Exception from "adb devices"')
+    return []
+  finally:
+    signal.alarm(0)
+
+
+def main(base_dir, adb_cmd='adb'):
+  """Monitor adb forever.  Expects a SIGINT (Ctrl-C) to kill."""
+  # 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
+    shutil.rmtree(base_dir, ignore_errors=True)
+
+  os.makedirs(base_dir)
+  logging.basicConfig(filename=os.path.join(base_dir, 'eventlog'),
+                      level=logging.INFO,
+                      format='%(asctime)-2s %(levelname)-8s %(message)s')
+
+  # Set up the alarm for calling 'adb devices'. This is to ensure
+  # our script doesn't get stuck waiting for a process response
+  def TimeoutHandler(_, unused_frame):
+    raise TimeoutException()
+  signal.signal(signal.SIGALRM, TimeoutHandler)
+
+  # Handle SIGTERMs to ensure clean shutdown
+  def SigtermHandler(_, unused_frame):
+    raise SigtermError()
+  signal.signal(signal.SIGTERM, SigtermHandler)
+
+  logging.info('Started with pid %d', os.getpid())
+  pid_file_path = os.path.join(base_dir, 'LOGCAT_MONITOR_PID')
+
+  try:
+    with open(pid_file_path, 'w') as f:
+      f.write(str(os.getpid()))
+    while True:
+      for device_id in GetAttachedDevices(adb_cmd):
+        if not device_id in devices:
+          devices[device_id] = (None, 0)
+
+      for device in devices:
+        # This will spawn logcat watchers for any device ever detected
+        StartLogcatIfNecessary(device, adb_cmd, base_dir)
+
+      time.sleep(5)
+  except SigtermError:
+    logging.info('Received SIGTERM, shutting down')
+  except:
+    logging.exception('Unexpected exception in main.')
+  finally:
+    for process, _ in devices.itervalues():
+      if process:
+        try:
+          process.terminate()
+        except OSError:
+          pass
+    os.remove(pid_file_path)
+
+
+if __name__ == '__main__':
+  if 2 <= len(sys.argv) <= 3:
+    print 'adb_logcat_monitor: Initializing'
+    sys.exit(main(*sys.argv[1:3]))
+
+  print 'Usage: %s <base_dir> [<adb_binary_path>]' % sys.argv[0]