[Telemetry] Refactor common Android test harness functions.

tools/telemetry/telemetry/core/backends/adb_commands.py

Index: tools/telemetry/telemetry/core/backends/adb_commands.py
diff --git a/tools/telemetry/telemetry/core/backends/adb_commands.py b/tools/telemetry/telemetry/core/backends/adb_commands.py
index 4dc52abf161b432d407b447e9c47dda50e0db6af..9d067cafef786d6ed56802813966af7c56c53e1f 100644
--- a/tools/telemetry/telemetry/core/backends/adb_commands.py
+++ b/tools/telemetry/telemetry/core/backends/adb_commands.py
@@ -23,7 +23,8 @@ try:
   from pylib import constants  # pylint: disable=F0401
   from pylib import forwarder  # pylint: disable=F0401
   from pylib import ports  # pylint: disable=F0401
-  from pylib.utils import apk_helper # #pylint: disable=F0401
+  from pylib.utils import apk_helper  # pylint: disable=F0401
+  from pylib.utils import test_environment  # pylint: disable=F0401
 except Exception:
   android_commands = None
 
@@ -40,6 +41,10 @@ def GetAttachedDevices():
   return android_commands.GetAttachedDevices()
 
 
+def CleanupLeftoverProcesses():
+  test_environment.CleanupLeftoverProcesses()
+
+
 def AllocateTestServerPort():
   return ports.AllocateTestServerPort()