devtools: fix unused import and whitespace in `android_shell.py`.

mojo/devtools/common/devtoolslib/android_shell.py

Index: mojo/devtools/common/devtoolslib/android_shell.py
diff --git a/mojo/devtools/common/devtoolslib/android_shell.py b/mojo/devtools/common/devtoolslib/android_shell.py
index ab03bb2b5e61fd0725dd34c17a17c36be683fa3d..91c26af7fb27c39fa1517ab50d604b01014c669b 100644
--- a/mojo/devtools/common/devtoolslib/android_shell.py
+++ b/mojo/devtools/common/devtoolslib/android_shell.py
@@ -4,7 +4,6 @@
 
 import atexit
 import hashlib
-import json
 import logging
 import os
 import os.path
@@ -67,6 +66,7 @@ def _find_available_host_port():
   netstat_output = subprocess.check_output(['netstat'])
   return _find_available_port(netstat_output)
 
+
 def parse_adb_devices_output(adb_devices_output):
   """Parses the output of the `adb devices` command, returning a dictionary
   mapping device id to the status of the device, as printed by `adb devices`.