Defer running of install_commands.Installed() until necessary

build/android/pylib/device/commands/install_commands.py

 # Copyright 2014 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.
 
 import os
+import posixpath
 
 from pylib import constants
 
 BIN_DIR = '%s/bin' % constants.TEST_EXECUTABLE_DIR
 _FRAMEWORK_DIR = '%s/framework' % constants.TEST_EXECUTABLE_DIR
 
 _COMMANDS = {
   'unzip': 'org.chromium.android.commands.unzip.Unzip',
 }
 
 _SHELL_COMMAND_FORMAT = (
 """#!/system/bin/sh
 base=%s
 export CLASSPATH=$base/framework/chromium_commands.jar
 exec app_process $base/bin %s $@
 """)
 
 
 def Installed(device):
-  return (all(device.FileExists('%s/%s' % (BIN_DIR, c)) for c in _COMMANDS)
-          and device.FileExists('%s/chromium_commands.jar' % _FRAMEWORK_DIR))
+  paths = [posixpath.join(BIN_DIR, c) for c in _COMMANDS]
+  paths.append(posixpath.join(_FRAMEWORK_DIR, 'chromium_commands.jar'))
+  return device.PathExists(paths)
+
 
 def InstallCommands(device):
   if device.IsUserBuild():
     raise Exception('chromium_commands currently requires a userdebug build.')
 
   chromium_commands_jar_path = os.path.join(
       constants.GetOutDirectory(), constants.SDK_BUILD_JAVALIB_DIR,
       'chromium_commands.dex.jar')
   if not os.path.exists(chromium_commands_jar_path):
     raise Exception('%s not found. Please build chromium_commands.'
                     % chromium_commands_jar_path)
 
   device.RunShellCommand(['mkdir', BIN_DIR, _FRAMEWORK_DIR])
   for command, main_class in _COMMANDS.iteritems():
     shell_command = _SHELL_COMMAND_FORMAT % (
         constants.TEST_EXECUTABLE_DIR, main_class)
     shell_file = '%s/%s' % (BIN_DIR, command)
     device.WriteFile(shell_file, shell_command)
     device.RunShellCommand(
         ['chmod', '755', shell_file], check_return=True)
 
   device.adb.Push(
       chromium_commands_jar_path,
       '%s/chromium_commands.jar' % _FRAMEWORK_DIR)