[Android] Handle unrun tests as a list rather than a set.

build/android/pylib/local/device/local_device_gtest_run.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.
 
 import collections
 import itertools
 import logging
 import os
 import posixpath
 
@@ skipping 408 matching lines @@
         if result.GetType() == base_test_result.ResultType.CRASH:
           if not resolved_tombstones:
             resolved_tombstones = '\n'.join(tombstones.ResolveTombstones(
                 device,
                 resolve_all_tombstones=True,
                 include_stack_symbols=False,
                 wipe_tombstones=True))
           result.SetTombstones(resolved_tombstones)
 
     not_run_tests = set(test).difference(set(r.GetName() for r in results))
-    return results, not_run_tests
+    return results, list(not_run_tests)
 
   #override
   def TearDown(self):
     @local_device_environment.handle_shard_failures
     def individual_device_tear_down(dev):
       for s in self._servers.get(str(dev), []):
         s.TearDown()
 
       tool = self.GetTool(dev)
       tool.CleanUpEnvironment()
 
     self._env.parallel_devices.pMap(individual_device_tear_down)