[Android] Add support for installing older versions of installed apks.

build/android/devil/android/sdk/adb_wrapper.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.
 
 """This module wraps Android's adb tool.
 
 This is a thin wrapper around the adb interface. Any additional complexity
 should be delegated to a higher level (ex. DeviceUtils).
 """
 
@@ skipping 420 matching lines @@
     Args:
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
 
     Returns:
       A list of PIDs as strings.
     """
     return [a.strip() for a in
             self._RunDeviceAdbCmd(['jdwp'], timeout, retries).split('\n')]
 
-  def Install(self, apk_path, forward_lock=False, reinstall=False,
-              sd_card=False, timeout=60*2, retries=_DEFAULT_RETRIES):
+  def Install(self, apk_path, forward_lock=False, allow_downgrade=False,
+              reinstall=False, sd_card=False, timeout=60*2,
+              retries=_DEFAULT_RETRIES):
     """Install an apk on the device.
 
     Args:
       apk_path: Host path to the APK file.
       forward_lock: (optional) If set forward-locks the app.
       reinstall: (optional) If set reinstalls the app, keeping its data.
       sd_card: (optional) If set installs on the SD card.
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
+      allow_downgrade: (optional) If set, allows for downgrades.

[jbudorick, 2015/12/08 16:44:56]

nit: same

[rnephew (Reviews Here), 2015/12/08 16:57:57]

Done.

     """
     VerifyLocalFileExists(apk_path)
     cmd = ['install']
     if forward_lock:
       cmd.append('-l')
     if reinstall:
       cmd.append('-r')
     if sd_card:
       cmd.append('-s')
+    if allow_downgrade:
+      cmd.append('-d')
     cmd.append(apk_path)
     output = self._RunDeviceAdbCmd(cmd, timeout, retries)
     if 'Success' not in output:
       raise device_errors.AdbCommandFailedError(
           cmd, output, device_serial=self._device_serial)
 
   def InstallMultiple(self, apk_paths, forward_lock=False, reinstall=False,
                       sd_card=False, allow_downgrade=False, partial=False,
                       timeout=60*2, retries=_DEFAULT_RETRIES):
     """Install an apk with splits on the device.
@@ skipping 184 matching lines @@
   @property
   def is_emulator(self):
     return _EMULATOR_RE.match(self._device_serial)
 
   @property
   def is_ready(self):
     try:
       return self.GetState() == _READY_STATE
     except device_errors.CommandFailedError:
       return False