Test Runner: Accept Chromium bot mode flag.

This is for compatiblity with Chrome's windowed test launcher.

Bug: angleproject:5417
Change-Id: I3a366b2b8aa895ab996fbcab68a777514038a206
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3644854
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Auto-Submit: Jamie Madill <jmadill@chromium.org>
diff --git a/src/tests/test_utils/runner/TestSuite.cpp b/src/tests/test_utils/runner/TestSuite.cpp
index ddc8fd8..26a7339 100644
--- a/src/tests/test_utils/runner/TestSuite.cpp
+++ b/src/tests/test_utils/runner/TestSuite.cpp
@@ -1388,6 +1388,7 @@
             ParseStringArg("--isolated_script_test_perf_output=", argument, &mHistogramJsonFile) ||
             ParseStringArg(kRenderTestOutputDir, argument, &mTestArtifactDirectory) ||
             ParseStringArg(kIsolatedOutDir, argument, &mTestArtifactDirectory) ||
+            ParseFlag("--test-launcher-bot-mode", argument, &mBotMode) ||
             ParseFlag("--bot-mode", argument, &mBotMode) ||
             ParseFlag("--debug-test-groups", argument, &mDebugTestGroups) ||
             ParseFlag(kGTestListTests, argument, &mGTestListTests) ||