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

build/android/adb_install_apk.py

 #!/usr/bin/env python
 #
 # 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.
 
 """Utility script to install APKs from the command line quickly."""
 
 import argparse
 import glob
@@ skipping 41 matching lines @@
   parser.add_argument('--release', action='store_const', const='Release',
                       dest='build_type',
                       help='If set, run test suites under out/Release. '
                            'Default is env var BUILDTYPE or Debug.')
   parser.add_argument('-d', '--device', dest='devices', action='append',
                       help='Target device for apk to install on. Enter multiple'
                            ' times for multiple devices.')
   parser.add_argument('--blacklist-file', help='Device blacklist JSON file.')
   parser.add_argument('-v', '--verbose', action='count',
                       help='Enable verbose logging.')
+  parser.add_argument('--downgrade', action='store_true',
+                      help='If set, allows downgrading of apk.')
 
   args = parser.parse_args()
 
   run_tests_helper.SetLogLevel(args.verbose)
   constants.SetBuildType(args.build_type)
 
   devil_chromium.Initialize(output_directory=constants.GetOutDirectory())
 
   apk = args.apk_path or args.apk_name
   if not apk.endswith('.apk'):
@@ skipping 24 matching lines @@
   if args.devices:
     devices = [d for d in devices if d in args.devices]
     if not devices:
       raise device_errors.DeviceUnreachableError(args.devices)
   elif not devices:
     raise device_errors.NoDevicesError()
 
   def blacklisting_install(device):
     try:
       if args.splits:
-        device.InstallSplitApk(apk, splits, reinstall=args.keep_data)
+        device.InstallSplitApk(apk, splits, reinstall=args.keep_data,
+                               allow_downgrade=args.downgrade)
       else:
-        device.Install(apk, reinstall=args.keep_data)
+        device.Install(apk, reinstall=args.keep_data,
+                       allow_downgrade=args.downgrade)
     except device_errors.CommandFailedError:
       logging.exception('Failed to install %s', args.apk_name)
       if blacklist:
         blacklist.Extend([str(device)], reason='install_failure')
         logging.warning('Blacklisting %s', str(device))
     except device_errors.CommandTimeoutError:
       logging.exception('Timed out while installing %s', args.apk_name)
       if blacklist:
         blacklist.Extend([str(device)], reason='install_timeout')
         logging.warning('Blacklisting %s', str(device))
 
   device_utils.DeviceUtils.parallel(devices).pMap(blacklisting_install)
 
 
 if __name__ == '__main__':
   sys.exit(main())