This is to prevent breakages like  https://crbug.com/922379  and  https://crbug.com/922889 .

Currently third_party/googletest/src is a DEPS in V8 and in Chromium, while the content of third_party/googletest/ (basically a BUILD.gn file) is forked and checked-in in both Chromium and V8.

We should make a subtreed from src/third_party/googletest and roll this into V8. Ideally it'd contain its own DEPS file and we'd use recursive DEPS to get src/third_party/googletest/src.