[benchmarking] remove shading environment variables before running gtests

Removing the variables which will confuse gtests.

Bug: chromium:1138988,1142435
Change-Id: Ied118e9350db38ba960ac6ac2cac75f5db601bf1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2504637
Commit-Queue: Wenbin Zhang <wenbinzhang@google.com>
Reviewed-by: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821888}

testing/scripts/run_performance_tests.py

@@ -281,6 +281,16 @@ def execute_gtest_perf_test(command_generator, output_paths, use_xvfb=False):
   # all the time on Linux.
   env[CHROME_SANDBOX_ENV] = CHROME_SANDBOX_PATH
   env['CHROME_HEADLESS'] = '1'
+  #TODO(crbug/1138988): Some gtests do not implements the unit_test_launcher.cc.
+  # As a result, they will not respect the arguments added by
+  # _generate_shard_args() and will still use the values of GTEST_SHARD_INDEX
+  # and GTEST_TOTAL_SHARDS to run part of the tests.
+  # Removing those environment variables as a workaround.
+  if command_generator._ignore_shard_env_vars:
+    if 'GTEST_TOTAL_SHARDS' in env:
+      env.pop('GTEST_TOTAL_SHARDS')
+    if 'GTEST_SHARD_INDEX' in env:
+      env.pop('GTEST_SHARD_INDEX')
 
   return_code = 0
   try:

tools/perf/scripts_smoke_unittest.py

@@ -371,6 +371,7 @@ class ScriptsSmokeTest(unittest.TestCase):
     class FakeCommandGenerator(object):
       def __init__(self):
         self.executable_name = 'binary_that_doesnt_exist'
+        self._ignore_shard_env_vars = False
 
       def generate(self, unused_path):
         return [self.executable_name]