Add histogram for HTTP response codes
Add histogram for HTTP response codes

This adds an histogram to the HTTP response header parser.  I reviewed
the code, and I've convinced myself that this captures the two main
cases of HTTP header parsing (tunneling, and normal HTTP), and that
double-calls aren't occuring.  I liked having all the code in the one
translation unit.  But, I might have missed one, and we might still
be getting called twice for the same load: so the statistics might be off.

Alternatively, I could put a static function on HttpResponseHeader, to
be called from the site of parse.  But this might miss a parse.

All in all, I wanted to be sure to catch all distinct response codes
we get, so we can be sure not to stomp on anything.  So I chose the
approach using the HttpResponseHeaders constructor.

TEST=none
BUG=70428

Review URL: http://codereview.chromium.org/6317011

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@72801 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser