Factor out a system_properties interface for interacting with getprop/setprop.

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

 # Copyright 2013 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.
 """Brings in Chrome Android's android_commands module, which itself is a
 thin(ish) wrapper around adb."""
 
 import logging
 import os
 import shutil
 import stat
@@ skipping 39 matching lines @@
 
 
 def ResetTestServerPortAllocation():
   return ports.ResetTestServerPortAllocation()
 
 
 class AdbCommands(object):
   """A thin wrapper around ADB"""
 
   def __init__(self, device):
-    self._adb = android_commands.AndroidCommands(device)
+    self._adb = android_commands.AndroidCommands(device, api_strict_mode=True)
     self._device = device
 
   def device(self):
     return self._device
 
+  @property
+  def system_properties(self):
+    return self._adb.system_properties
+
   def Adb(self):
     return self._adb
 
   def Forward(self, local, remote):
     ret = self._adb.Adb().SendCommand('forward %s %s' % (local, remote))
     assert ret == ''
 
   def RunShellCommand(self, command, timeout_time=20, log_result=False):
     """Send a command to the adb shell and return the result.
 
@@ skipping 110 matching lines @@
     if os.path.join(build_dir, build_type) in path:
       return build_type
   return None
 
 
 def SetupPrebuiltTools(adb):
   # TODO(bulach): build the host tools for mac, and the targets for x86/mips.
   # Prebuilt tools from r226197.
   has_prebuilt = sys.platform.startswith('linux')
   if has_prebuilt:
-    abi = adb.RunShellCommand('getprop ro.product.cpu.abi')
-    has_prebuilt = abi and abi[0].startswith('armeabi')
+    abi = adb.system_properties['ro.product.cpu.abi']
+    has_prebuilt = abi.startswith('armeabi')
   if not has_prebuilt:
     logging.error(
         'Prebuilt android tools only available for Linux host and ARM device.')
     return False
 
   prebuilt_tools = [
       'forwarder_dist/device_forwarder',
       'host_forwarder',
       'md5sum_dist/md5sum_bin',
       'md5sum_bin_host',
@@ skipping 35 matching lines @@
     self._port_pairs = new_port_pairs
     forwarder.Forwarder.Map(new_port_pairs, self._adb)
 
   @property
   def url(self):
     return 'http://127.0.0.1:%i' % self._host_port
 
   def Close(self):
     for (device_port, _) in self._port_pairs:
       forwarder.Forwarder.UnmapDevicePort(device_port, self._adb)