Typical timing for running content_shell directly:

out/Default/content_shell --run-web-tests third_party/WebKit/LayoutTests/external/wpt/webrtc/RTCCertificate.html

real	0m3.095s
user	0m2.424s
sys	0m0.312s

Using run_web_tests:

real	0m18.421s
user	0m13.135s
sys	0m2.035s

In addition, if there are changes to the output, I have to find the browser window that the test output was piped into and click buttons in order to display the output; when using content_shell, I can see the PASS / FAIL lines directly in my terminal window.

But run_web_tests contains much magic that just calling content_shell will not achieve.

A simpler, faster way of running tests while debugging would be appreciated.