Restore modified shared pref settings after tests

Changes the behavior of instrumentation tests to automatically
restore any shared preference files modified by
--shared-prefs-file. Also adds a simple script for manually
applying a shared preference JSON file for cases where settings
that are normally only used during automated testing are
needed for manual use.

Change-Id: I94006c1a8e48d910ed2f7e0742f001d8d62b7b15
Reviewed-on: https://chromium-review.googlesource.com/1220557Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593218}

build/android/apply_shared_preference_file.py

+#!/usr/bin/env python
+#
+# Copyright 2018 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.
+
+"""Manually applies a shared preference JSON file.
+
+If needed during automation, use the --shared-prefs-file in test_runner.py
+instead.
+"""
+
+import argparse
+import sys
+
+# pylint: disable=ungrouped-imports
+from pylib.constants import host_paths
+if host_paths.DEVIL_PATH not in sys.path:
+  sys.path.append(host_paths.DEVIL_PATH)
+
+from devil.android import device_utils
+from devil.android.sdk import shared_prefs
+from pylib.utils import shared_preference_utils
+
+
+def main():
+  parser = argparse.ArgumentParser(
+      description='Manually apply shared preference JSON files.')
+  parser.add_argument('filepaths', nargs='*',
+                      help='Any number of paths to shared preference JSON '
+                           'files to apply.')
+  args = parser.parse_args()
+
+  all_devices = device_utils.DeviceUtils.HealthyDevices()
+  if not all_devices:
+    raise RuntimeError('No healthy devices attached')
+
+  for filepath in args.filepaths:
+    all_settings = shared_preference_utils.ExtractSettingsFromJson(filepath)
+    for setting in all_settings:
+      for device in all_devices:
+        shared_pref = shared_prefs.SharedPrefs(
+            device, setting['package'], setting['filename'],
+            use_encrypted_path=setting.get('supports_encrypted_path', False))
+        shared_preference_utils.ApplySharedPreferenceSetting(
+            shared_pref, setting)
+
+
+if __name__ == '__main__':
+  main()

build/android/pylib/local/device/local_device_instrumentation_test_run.py

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import contextlib
+import copy
 import hashlib
 import json
 import logging
@@ -126,6 +127,7 @@ class LocalDeviceInstrumentationTestRun(
         env, test_instance)
     self._flag_changers = {}
     self._replace_package_contextmanager = None
+    self._shared_prefs_to_restore = []
 
   #override
   def TestPackage(self):
@@ -226,6 +228,10 @@ class LocalDeviceInstrumentationTestRun(
           shared_pref = shared_prefs.SharedPrefs(
               dev, setting['package'], setting['filename'],
               use_encrypted_path=setting.get('supports_encrypted_path', False))
+          pref_to_restore = copy.copy(shared_pref)
+          pref_to_restore.Load()
+          self._shared_prefs_to_restore.append(pref_to_restore)
+
           shared_preference_utils.ApplySharedPreferenceSetting(
               shared_pref, setting)
 
@@ -311,6 +317,13 @@ class LocalDeviceInstrumentationTestRun(
 
       valgrind_tools.SetChromeTimeoutScale(dev, None)
 
+      # Restore any shared preference files that we stored during setup.
+      # This should be run sometime before the replace package contextmanager
+      # gets exited so we don't have to special case restoring files of
+      # replaced system apps.
+      for pref_to_restore in self._shared_prefs_to_restore:
+        pref_to_restore.Commit(force_commit=True)
+
       if self._replace_package_contextmanager:
         # See pylint-related commend above with __enter__()
         # pylint: disable=no-member

chrome/android/javatests/src/org/chromium/chrome/browser/vr/README.md

@@ -151,11 +151,12 @@ headset. The two most common files used are:
   emulation.
 * `//chrome/android/shared_preference_files/test/vr_ddview_skipdon_setupcomplete.json`
   This will pair the device with a Daydream View headset, set the DON flow to be
-  skipped, and enable controller emulation. **NOTE** This will prevent you from
-  using a real controller outside of tests. To fix this, you can either
-  reinstall VrCore or apply the Cardboard settings file (there isn't currently a
-  way to manually re-enable real controller use from within the VrCore developer
-  settings)
+  skipped, and enable controller emulation.
+
+The test runner will automatically revert any changed settings back to their
+pre-test values after the test suite has completed. If for whatever reason you
+want to manually apply settings outside of a test, you can do so with
+`//build/android/apply_shared_preference_file.py`.
 
 #### vr-settings-service-enabled