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

build/android/devil/android/device_utils.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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=unused-argument
 
@@ skipping 526 matching lines @@
     self.adb.Reboot()
     self._ClearCache()
     timeout_retry.WaitFor(device_offline, wait_period=1)
     if block:
       self.WaitUntilFullyBooted(wifi=wifi)
 
   INSTALL_DEFAULT_TIMEOUT = 4 * _DEFAULT_TIMEOUT
 
   @decorators.WithTimeoutAndRetriesFromInstance(
       min_default_timeout=INSTALL_DEFAULT_TIMEOUT)
-  def Install(self, apk, reinstall=False, permissions=None, timeout=None,
-              retries=None):
+  def Install(self, apk, allow_downgrade=False, reinstall=False,
+              permissions=None, timeout=None, retries=None):
     """Install an APK.
 
     Noop if an identical APK is already installed.
 
     Args:
       apk: An ApkHelper instance or string containing the path to the APK.
+      allow_downgrade: A boolean indicating if we should allow downgrades.
+      reinstall: A boolean indicating if we should keep any existing app data.
       permissions: Set of permissions to set. If not set, finds permissions with
           apk helper. To set no permissions, pass [].
-      reinstall: A boolean indicating if we should keep any existing app data.
       timeout: timeout in seconds
       retries: number of retries
 
     Raises:
       CommandFailedError if the installation fails.
       CommandTimeoutError if the installation times out.
       DeviceUnreachableError on missing device.
     """
-    self._InstallInternal(apk, None, reinstall=reinstall,
-                          permissions=permissions)
+    self._InstallInternal(apk, None, allow_downgrade=allow_downgrade,
+                          reinstall=reinstall, permissions=permissions)
 
   @decorators.WithTimeoutAndRetriesFromInstance(
       min_default_timeout=INSTALL_DEFAULT_TIMEOUT)
-  def InstallSplitApk(self, base_apk, split_apks, reinstall=False,
-                      allow_cached_props=False, permissions=None, timeout=None,
-                      retries=None):
+  def InstallSplitApk(self, base_apk, split_apks, allow_downgrade=False,
+                      reinstall=False, allow_cached_props=False,
+                      permissions=None, timeout=None, retries=None):
     """Install a split APK.
 
     Noop if all of the APK splits are already installed.
 
     Args:
       base_apk: An ApkHelper instance or string containing the path to the base
           APK.
       split_apks: A list of strings of paths of all of the APK splits.
+      allow_downgrade: A boolean indicating if we should allow downgrades.
       reinstall: A boolean indicating if we should keep any existing app data.
       allow_cached_props: Whether to use cached values for device properties.
       permissions: Set of permissions to set. If not set, finds permissions with
           apk helper. To set no permissions, pass [].
       timeout: timeout in seconds
       retries: number of retries
 
     Raises:
       CommandFailedError if the installation fails.
       CommandTimeoutError if the installation times out.
       DeviceUnreachableError on missing device.
       DeviceVersionError if device SDK is less than Android L.
     """
     self._InstallInternal(base_apk, split_apks, reinstall=reinstall,
                           allow_cached_props=allow_cached_props,
-                          permissions=permissions)
+                          permissions=permissions,
+                          allow_downgrade=allow_downgrade)
 
-  def _InstallInternal(self, base_apk, split_apks, reinstall=False,
-                       allow_cached_props=False, permissions=None):
+  def _InstallInternal(self, base_apk, split_apks, allow_downgrade=False,
+                       reinstall=False, allow_cached_props=False,
+                       permissions=None):
     if split_apks:
       self._CheckSdkLevel(version_codes.LOLLIPOP)
 
     base_apk = apk_helper.ToHelper(base_apk)
 
     all_apks = [base_apk.path]
     if split_apks:
       all_apks += split_select.SelectSplits(
         self, base_apk.path, split_apks, allow_cached_props=allow_cached_props)
       if len(all_apks) == 1:
@@ skipping 25 matching lines @@
         self.Uninstall(package_name)
         apks_to_install = all_apks
 
     if apks_to_install:
       # Assume that we won't know the resulting device state.
       self._cache['package_apk_paths'].pop(package_name, 0)
       self._cache['package_apk_checksums'].pop(package_name, 0)
       if split_apks:
         partial = package_name if len(apks_to_install) < len(all_apks) else None
         self.adb.InstallMultiple(
-            apks_to_install, partial=partial, reinstall=reinstall)
+            apks_to_install, partial=partial, reinstall=reinstall,
+            allow_downgrade=allow_downgrade)
       else:
-        self.adb.Install(base_apk.path, reinstall=reinstall)
+        self.adb.Install(
+            base_apk.path, reinstall=reinstall, allow_downgrade=allow_downgrade)
       if (permissions is None
           and self.build_version_sdk >= version_codes.MARSHMALLOW):
         permissions = base_apk.GetPermissions()
       self.GrantPermissions(package_name, permissions)
       # Upon success, we know the device checksums, but not their paths.
       if host_checksums is not None:
         self._cache['package_apk_checksums'][package_name] = host_checksums
     else:
       # Running adb install terminates running instances of the app, so to be
       # consistent, we explicitly terminate it when skipping the install.
@@ skipping 1492 matching lines @@
       on: bool to decide state to switch to. True = on False = off.
     """
     def screen_test():
       return self.IsScreenOn() == on
 
     if screen_test():
       logging.info('Screen already in expected state.')
       return
     self.RunShellCommand('input keyevent 26')
     timeout_retry.WaitFor(screen_test, wait_period=1)