[build/android] Load/dump pickles directly form/to files

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

 # Copyright 2016 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 io
 import json
 import logging
 import os
 import pickle
@@ skipping 188 matching lines @@
         logging.info('%d files in the output dir were archived.', num_files)
       else:
         logging.warning('No files in the output dir. Archive is empty.')
       return archive.getvalue()
 
   @staticmethod
   def _SaveResult(result):
     pickled = os.path.join(constants.PERF_OUTPUT_DIR, result['name'])
     if os.path.exists(pickled):
       with file(pickled, 'r') as f:
-        previous = pickle.loads(f.read())
+        previous = pickle.load(f)
         result['output'] = previous['output'] + result['output']
     with file(pickled, 'w') as f:
-      f.write(pickle.dumps(result))
+      pickle.dump(result, f)
 
   def _TestTearDown(self):
     if self._output_dir:
       shutil.rmtree(self._output_dir, ignore_errors=True)
       self._output_dir = None
     self._heart_beat.Stop()
     self._current_test = None
 
   @property
   def current_test(self):
@@ skipping 306 matching lines @@
   # override
   def _RunTest(self, _device, _test):
     raise NotImplementedError
 
 
 class TestDictVersionError(Exception):
   pass
 
 class PerfTestRunGetStepsError(Exception):
   pass