Add browser controller and allow it to be used under a flag.
Add browser controller and allow it to be used under a flag.

This is currently chrome and firefox only.

I am still seeing a race condition occasionally, which is the reason
for the rather verbose prints I do when failing.

I have not added prefetching yet, I will do that as a next step.

R=kustermann@google.com

Review URL: https://codereview.chromium.org//14757019

git-svn-id: b889c0189f1adfea19efba192a3d7a5b889e4120@22675 260f80e4-7a28-3924-810f-c04153c831b5

Pacane/test,apwilson/test,d2m/test,d2m/test,apwilson/test,greglittlefield-wf/test,Pacane/test,kevmoo/test,d2m/test,kevmoo/test,iglherme/Guttiest,iglherme/Guttiest,grouma/test,iglherme/Guttiest,greglittlefield-wf/test,kevmoo/test,greglittlefield-wf/test,grouma/test,apwilson/test,grouma/test