Mange ciricular reference to HttpNetworkTransaction in HttpProxyClientSocktPool.
Mange ciricular reference to HttpNetworkTransaction in HttpProxyClientSocktPool.

Without explicit management of the cirucular reference to HttpNetworkTransaction, it can get deleted at inopportune times and cause undesirable effects (i.e. triggering a pool to delete itself while in the middle of other operations).  This change breaks the cirucular reference at points in execution where it is safe.

BUG=50822, 49254
TEST=green reliability bot

Review URL: http://codereview.chromium.org/3084011

git-svn-id: http://src.chromium.org/svn/trunk/src@54715 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 9aa9ba961ad7481ffea619f4fba7e90bc62b3e52
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