[Android] Add GetDescription and defer calculating device_utc_offset

build/android/pylib/android_commands.py

 # Copyright (c) 2012 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.
 
 """Provides an interface to communicate with the device via the adb command.
 
 Assumes adb binary is currently on system path.
 """
 
 import collections
@@ skipping 201 matching lines @@
       # Required by third_party/android_testrunner to call directly 'adb'.
       os.environ['PATH'] += os.pathsep + adb_dir
     self._adb = adb_interface.AdbInterface()
     if device:
       self._adb.SetTargetSerial(device)
     self._device = device
     self._logcat = None
     self.logcat_process = None
     self._logcat_tmpoutfile = None
     self._pushed_files = []
-    self._device_utc_offset = self.RunShellCommand('date +%z')[0]
+    self._device_utc_offset = None
     self._md5sum_build_dir = ''
     self._external_storage = ''
     self._util_wrapper = ''
 
   def _LogShell(self, cmd):
     """Logs the adb shell command."""
     if self._device:
       device_repr = self._device[-4:]
     else:
       device_repr = '????'
@@ skipping 608 matching lines @@
     # -rw-r----- 1 user group   102 2011-05-12 12:29:54.131623387 +0100 baz.txt
     re_file = re.compile('^-(?P<perms>[^\s]+)\s+'
                          '(?P<user>[^\s]+)\s+'
                          '(?P<group>[^\s]+)\s+'
                          '(?P<size>[^\s]+)\s+'
                          '(?P<date>[^\s]+)\s+'
                          '(?P<time>[^\s]+)\s+'
                          '(?P<filename>[^\s]+)$')
     return _GetFilesFromRecursiveLsOutput(
         path, self.RunShellCommand('ls -lR %s' % path), re_file,
-        self._device_utc_offset)
+        self.GetUtcOffset())
+
+  def GetUtcOffset(self):
+    if not self._device_utc_offset:
+      self._device_utc_offset = self.RunShellCommand('date +%z')[0]
+    return self._device_utc_offset
 
   def SetJavaAssertsEnabled(self, enable):
     """Sets or removes the device java assertions property.
 
     Args:
       enable: If True the property will be set.
 
     Returns:
       True if the file was modified (reboot is required for it to take effect).
     """
@@ skipping 29 matching lines @@
     build_id = self.RunShellCommand('getprop ro.build.id')[0]
     assert build_id
     return build_id
 
   def GetBuildType(self):
     """Returns the build type of the system (e.g. eng)."""
     build_type = self.RunShellCommand('getprop ro.build.type')[0]
     assert build_type
     return build_type
 
+  def GetDescription(self):
+    """Returns the description of the system.
+
+    For example, "yakju-userdebug 4.1 JRN54F 364167 dev-keys".
+    """
+    description = self.RunShellCommand('getprop ro.build.description')[0]
+    assert description
+    return description
+
   def GetProductModel(self):
-    """Returns the namve of the product model (e.g. "Galaxy Nexus") """
+    """Returns the name of the product model (e.g. "Galaxy Nexus") """
     model = self.RunShellCommand('getprop ro.product.model')[0]
     assert model
     return model
 
   def StartMonitoringLogcat(self, clear=True, logfile=None, filters=None):
     """Starts monitoring the output of logcat, for use with WaitForLogMatch.
 
     Args:
       clear: If True the existing logcat output will be cleared, to avoiding
              matching historical output lurking in the log.
@@ skipping 424 matching lines @@
   """
   def __init__(self, output):
     self._output = output
 
   def write(self, data):
     data = data.replace('\r\r\n', '\n')
     self._output.write(data)
 
   def flush(self):
     self._output.flush()