Revert 90373 - Warmth of a connection (cwnd) is estimated by the amount of data written to the so...

Revert 90373 - Warmth of a connection (cwnd) is estimated by the amount of data written to the socket. 
Choosing the warmest connection would mean faster resource load times. 

Caused layout tests http/tests/loading/redirect-methods.html and http/tests/security/xss-DENIED-iframe-src-alias.html fail on deps WebKit bots, and caused http://code.google.com/p/chromium/issues/detail?id=87423

Deps bots failures: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20-%20chromium.org&tests=http%2Ftests%2Floading%2Fredirect-methods.html%2Chttp%2Ftests%2Fsecurity%2Fxss-DENIED-iframe-src-alias.html

idle time is the time a socket has remained idle (no http requests being served on it). 
Probability of server resetting a connection increases with idle time duration. 

Using a cost function that takes into account bytes transferred and idle time to pick best connection to schedule http requests on.

CODEREVIEW done in http://codereview.chromium.org/6990036/

Contributed by gagansingh@google.com

Review URL: http://codereview.chromium.org/7189055

TBR=gagansingh@google.com
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=90389