Pass a user agent string to WinHttpOpen to set the user agent string on the session handle, which is the only way to specify the User-Agent header for HTTP CONNECT requests.
Pass a user agent string to WinHttpOpen to set the user
agent string on the session handle, which is the only
way to specify the User-Agent header for HTTP CONNECT
requests.

This requires some refactoring.  Most of the work done
by Session::Init() is moved to the Session constructor.
Session::Init() now only creates the primary session
handle, and the call to Session::Init() is delayed to
the first time we use the primary session handle
(session_->internet()).

R=darin
BUG=552
Review URL: http://codereview.chromium.org/8841

git-svn-id: http://src.chromium.org/svn/trunk/src@4114 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: e8ad78d751b677ab0190dce3e20e6c997d98464f
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser