Add a simple NavigateMeasurement to measure time taken in navigate_steps

This is useful for pages (such as chromestatus.com) where the 'load' event
is not a good signal for 'page ready', but where there's some other condition,
easily expressible in navigate_steps, of that readiness.

R=dtu@chromium.org

Review URL: https://codereview.chromium.org/108303010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241888 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241888
Enable SPDY explicitly.

SPDY does not seem to be enabled by default. Enable it explicitly.

Review URL: https://codereview.chromium.org/106903017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241889 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241889