[iOS][infra] Use GTest with xctest for all on device GTests.

Previously this was only used for iOS 13+ device. This CL changes it for
all on device GTests and remove the iOS version check method.
This CL only prepares to run these in test runner scripts. Will send
follow up CLs on GN configs to make device builders really build and
run GTests with xctest.

Bug: 1087078, 1001667
Change-Id: I03386ec0caa6f719640cb4d8140cb73ded0ef2c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2219108
Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772548}

ios/build/bots/scripts/test_runner.py

@@ -158,19 +158,6 @@ def get_device_ios_version(udid):
                                   '-k', 'ProductVersion']).strip()
 
 
-def is_iOS13_or_higher_device(udid):
-  """Checks whether device with udid has iOS 13.0+.
-
-  Args:
-    udid: (str) iOS device UDID.
-
-  Returns:
-    True for iOS 13.0+ devices otherwise false.
-  """
-  return (distutils.version.LooseVersion(get_device_ios_version(udid)) >=
-          distutils.version.LooseVersion('13.0'))
-
-
 def defaults_write(d, key, value):
   """Run 'defaults write d key value' command.
 
@@ -316,10 +303,16 @@ def get_xctest_from_app(app):
   """
   plugins_dir = os.path.join(app, 'PlugIns')
   if not os.path.exists(plugins_dir):
+    # TODO(crbug.com/1001667): Throw error when all device unit test should run
+    # with xctest.
+    LOGGER.warning('PlugIns dir doesn\'t exist in app.\n')
     return None
   for plugin in os.listdir(plugins_dir):
     if plugin.endswith('.xctest'):
       return os.path.join(plugins_dir, plugin)
+  # TODO(crbug.com/1001667): Throw error when all device unit test should run
+  # with xctest.
+  LOGGER.warning('.xctest doesn\'t exist in app PlugIns dir.\n')
   return None
 
 
@@ -579,7 +572,7 @@ class TestRunner(object):
       if self.__class__.__name__ == 'DeviceTestRunner':
         # When self.xctest is False and (bool)self.xctest_path is True and it's
         # using a device runner, this is a XCTest hosted unit test, which is
-        # currently running on iOS 13+ devices.
+        # currently running on real devices.
         # TODO(crbug.com/1006881): Separate "running style" from "parser style"
         # for XCtests and Gtests.
         test_app = test_apps.DeviceXCTestUnitTestsApp(
@@ -980,13 +973,10 @@ class DeviceTestRunner(TestRunner):
     if len(self.udid.splitlines()) != 1:
       raise DeviceDetectionError(self.udid)
 
-    is_iOS13 = is_iOS13_or_higher_device(self.udid)
-
-    # GTest-based unittests are invoked via XCTest on iOS 13+ devices
+    # GTest-based unittests are invoked via XCTest for all devices
     # but produce GTest-style log output that is parsed with a GTestLogParser.
-    if xctest or is_iOS13:
-      if is_iOS13:
-        self.xctest_path = get_xctest_from_app(self.app_path)
+    self.xctest_path = get_xctest_from_app(self.app_path)
+
     self.restart = restart
 
   def uninstall_apps(self):

ios/build/bots/scripts/xcodebuild_runner_test.py

@@ -210,7 +210,6 @@ class DeviceXcodeTestRunnerTest(test_runner_test.TestCase):
     self.mock(test_runner.TestRunner, 'set_sigterm_handler',
               lambda self, handler: 0)
     self.mock(os, 'listdir', lambda _: [])
-    self.mock(test_runner, 'is_iOS13_or_higher_device', lambda _: False)
     self.mock(test_runner, 'print_process_output', lambda _: [])
     self.mock(test_runner.TestRunner, 'start_proc', lambda self, cmd: 0)
     self.mock(test_runner.DeviceTestRunner, 'get_installed_packages',