Logdog for logcats

build/android/pylib/local/device/local_device_environment.py

Index: build/android/pylib/local/device/local_device_environment.py
diff --git a/build/android/pylib/local/device/local_device_environment.py b/build/android/pylib/local/device/local_device_environment.py
index 431614377efa68bd4cffecc6158f13d0d6673965..eb9ed1a4e45e8d715e62edb4fde659ed47682aca 100644
--- a/build/android/pylib/local/device/local_device_environment.py
+++ b/build/android/pylib/local/device/local_device_environment.py
@@ -188,6 +188,12 @@ class LocalDeviceEnvironment(environment.Environment):
       try:
         m.Stop()
         m.Close()
+        _, temp_path = tempfile.mkstemp()
+        with open(m.output_file, 'r') as infile:
+          with open(temp_path, 'w') as outfile:
+            for line in infile:
+              outfile.write('Device(%s) %s' % (m.adb.GetDeviceSerial(), line))
+        shutil.move(temp_path, m.output_file)
       except base_error.BaseError:
         logging.exception('Failed to stop logcat monitor for %s',
                           m.adb.GetDeviceSerial())