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

tools/battor_agent/BUILD.gn

Index: tools/battor_agent/BUILD.gn
diff --git a/tools/battor_agent/BUILD.gn b/tools/battor_agent/BUILD.gn
index 1a057f3f2b0336b1c5ae5e984c912600c6846f6c..12fb7d5dbb0607a6b9ea31bc68997171e6b760b1 100644
--- a/tools/battor_agent/BUILD.gn
+++ b/tools/battor_agent/BUILD.gn
@@ -59,3 +59,12 @@
     "//testing/gtest",
   ]
 }
+
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("battor_agent_unittests_run") {
+  testonly = true
+  deps = [
+    ":battor_agent_unittests",
+  ]
+}