Use vpython rather than python for GPU tests on the bots.

From talking with iannucci@, this is the easiest way to use vpython
with these tests on the bots. Once the LUCI conversion is done, this
will be a no-op, and can be removed.

Incorporate the newly deployed pyobjc wheels into Chromium's root
.vpython; they are needed by helper scripts in the GPU directory.

Bug: 776804, 804174
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I1c720a9f7992e411aa85bcc7959de95ecc03c1f5
Reviewed-on: https://chromium-review.googlesource.com/869512Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533226}

.vpython

@@ -124,3 +124,19 @@ wheel: <
   name: "infra/python/wheels/simplejson/${vpython_platform}"
   version: "version:3.13.2"
 >
+
+# Used by:
+#   content/test/gpu/gpu_tests/color_profile_manager_mac.py
+wheel: <
+  name: "infra/python/wheels/pyobjc/${vpython_platform}"
+  version: "version:4.1"
+  match_tag: < platform: "macosx_10_10_intel" >
+>
+# TODO(crbug.com/804174): roll out support in vpython for
+# "not_match_tag", then uncomment this.
+# wheel: <
+#   name: "infra/python/wheels/pyobjc/${vpython_platform}"
+#   version: "version:2.5.1"
+#   match_tag: < platform: "macosx_10_6_intel" >
+#   not_match_tag: < platform: "macosx_10_10_intel" >
+# >

testing/scripts/run_gpu_integration_test_as_googletest.py

@@ -104,7 +104,10 @@ def main():
     rc = 0
     try:
       env['CHROME_HEADLESS'] = '1'
-      rc = common.run_command([sys.executable] + rest_args + sharding_args + [
+      main_command = [sys.executable]
+      if not os.getenv('VIRTUAL_ENV'):
+        main_command = ['vpython']
+      rc = common.run_command(main_command + rest_args + sharding_args + [
         '--write-full-results-to', args.isolated_script_test_output
       ], env=env)
     except Exception: