Revert 167539 "Updating Blink-side Gamepad API to match latest spec"

Compiler errors introduced on Blink waterfall

> Updating Blink-side Gamepad API to match latest spec
> 
> BUG=344556
> R=abarth@chromium.org, scottmg@chromium.org
> 
> Review URL: https://codereview.chromium.org/170993002

TBR=bajones@chromium.org

Review URL: https://codereview.chromium.org/171423019

git-svn-id: svn://svn.chromium.org/blink/trunk@167541 bbb929c8-8fbe-4397-9dbb-9b2b20218538