chromeos: Switch Tast result parser to use streamed_results.jsonl.

This should let us parse some results even if something goes wrong
and the final results.json doesn't get generated for some reason.

Bug: 923426
Change-Id: I028896c9edc7aeb8b3ec6339b8867f0b29ae095f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575105Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654678}

.vpython

@@ -25,7 +25,14 @@
 python_version: "2.7"
 
 # Used by:
-#   build/chromeos/run_vm_test.py
+#   build/chromeos/test_runner.py
+wheel: <
+  name: "infra/python/wheels/jsonlines-py2_py3"
+  version: "version:1.2.0"
+>
+
+# Used by:
+#   build/chromeos/test_runner.py
 #   third_party/catapult
 #
 # This version must be compatible with the version range specified by

build/chromeos/test_runner.py

@@ -5,6 +5,7 @@
 # found in the LICENSE file.
 
 import argparse
+import collections
 import json
 import logging
 import os
@@ -18,6 +19,7 @@ import tempfile
 # The following non-std imports are fetched via vpython. See the list at
 # //.vpython
 import dateutil.parser  # pylint: disable=import-error
+import jsonlines  # pylint: disable=import-error
 import psutil  # pylint: disable=import-error
 
 CHROMIUM_SRC_PATH = os.path.abspath(os.path.join(
@@ -325,9 +327,7 @@ class TastTest(RemoteTest):
     if not self._use_host_tast:
       return super(TastTest, self).post_run(return_code)
 
-    # TODO(crbug.com/952085): Switch to streamed_results.jsonl after jsonlines
-    # becomes available as a wheel.
-    tast_results_path = os.path.join(self._logs_dir, 'results.json')
+    tast_results_path = os.path.join(self._logs_dir, 'streamed_results.jsonl')
     if not os.path.exists(tast_results_path):
       logging.error(
          'Tast results not found at %s. Falling back to generic result '
@@ -336,8 +336,8 @@ class TastTest(RemoteTest):
 
     # See the link below for the format of the results:
     # https://godoc.org/chromium.googlesource.com/chromiumos/platform/tast.git/src/chromiumos/cmd/tast/run#TestResult
-    with open(tast_results_path) as f:
-      tast_results = json.load(f)
+    with jsonlines.open(tast_results_path) as reader:
+      tast_results = collections.deque(reader)
 
     suite_results = base_test_result.TestRunResults()
     for test in tast_results: