Android gtest runner: Query only a single device for the test list

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

Index: build/android/pylib/local/device/local_device_gtest_run.py
diff --git a/build/android/pylib/local/device/local_device_gtest_run.py b/build/android/pylib/local/device/local_device_gtest_run.py
index 0f360d4a9e943045c946f68689f98788fd2966e9..9369959ed2af3e17900d073976d8106356a15d50 100644
--- a/build/android/pylib/local/device/local_device_gtest_run.py
+++ b/build/android/pylib/local/device/local_device_gtest_run.py
@@ -229,9 +229,8 @@ class LocalDeviceGtestRun(local_device_test_run.LocalDeviceTestRun):
       tests = self._test_instance.FilterTests(tests)
       return tests
 
-    test_lists = self._env.parallel_devices.pMap(list_tests).pGet(None)
-    tests = list(sorted(set().union(*[set(tl) for tl in test_lists if tl])))
-    return tests
+    # Result should be the same for all devices, so just use the first one.
+    return list_tests(self._env.devices[0])
 
   #override
   def _RunTest(self, device, test):