Repro steps:
1) Sign into Chrome
2) Go to MD settings and click "Sign out"
3) Observe the default highlight in the "Sign out of Chrome" confirmation dialogue

We probably shouldn't be highlighting "Google dashboard" by default. Ideally, I think nothing should be highlighted by default, but pressing "Enter" should interact with the default "Sign out" blue button.

cc'ing some sign-in folks as FYI, Mihai since we have a similar issue in a web UI dialogue, and Moe since I think he helped implement this dialogue.