Revert of Move gn _run target generation into test().

chrome/test/chromedriver/BUILD.gn

Index: chrome/test/chromedriver/BUILD.gn
diff --git a/chrome/test/chromedriver/BUILD.gn b/chrome/test/chromedriver/BUILD.gn
index 1684a67458528f846a255301011af35eba32ef6b..435b6349e5d856e672975c12dd2c63caec0df87b 100644
--- a/chrome/test/chromedriver/BUILD.gn
+++ b/chrome/test/chromedriver/BUILD.gn
@@ -190,6 +190,15 @@
   ]
 }
 
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("chromedriver_unittests_run") {
+  testonly = true
+  deps = [
+    ":chromedriver_unittests",
+  ]
+}
+
 test("chromedriver_unittests") {
   sources =
       rebase_path(chrome_tests_gypi_values.chrome_driver_unittests_sources,