Fix KeyError caused when filtering gtests on multiple threads.

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 6796734c7d6a38f24651011b7ed7ca5b2d22378a..a8a8fb7e546d4daa002eabab1f44ffa69a019983 100644
--- a/build/android/pylib/local/device/local_device_gtest_run.py
+++ b/build/android/pylib/local/device/local_device_gtest_run.py
@@ -338,12 +338,14 @@ class LocalDeviceGtestRun(local_device_test_run.LocalDeviceTestRun):
         logging.info('No tests found. Output:')
         for l in raw_test_list:
           logging.info('  %s', l)
-      tests = self._test_instance.FilterTests(tests)
       return tests
 
-    # Query all devices in case one fails.
+    # Query all devices in case one fails. Return unfiltered test list
+    # because |FilterTests| function is not threadsafe on older versions
+    # of python due to its use of |fnmatch| module.
     test_lists = self._env.parallel_devices.pMap(list_tests).pGet(None)
-
+    test_lists = [self._test_instance.FilterTests(tests)

[jbudorick, 2016/11/17 00:16:03]

This change is ok, but it should also either:
 - make FilterTests threadsafe
 - add a comment in FilterTests's docstring explaining that it isn't threadsafe
and why.

+                  for tests in test_lists]
     # If all devices failed to list tests, raise an exception.
     # Check that tl is not None and is not empty.
     if all(not tl for tl in test_lists):