Re-add resource speculative prefetching code
This CL fixes the memory leak bug in CL
462423004.
See https://codereview.chromium.org/
462423004/ for previous code reviews.
-------------------------
Original CL description
-------------------------
Revert CL
117933003. Re-add speculative resource prefetching code.
https://codereview.chromium.org/
117933003/
The speculative resource prefetching code was experimental code developed by
shishir@. He found that it has little improvement on desktop Chrome (win). We
though this should be beneficial to mobile browsers. After discussing with
tburkard@ and kenjibaheux@, we decided to bring the code back and do more
analysis on mobile devices. Reverting the patchset to re-add the code is the
first step.
The following design doc has discussed all related approaches and action items.
https://docs.google.com/a/google.com/document/d/1ie3hu-zNNXvmTXm3aJAtKUGOh6nZfbNjA0aZE1bzzIg/edit?usp=sharing
BUG=408399, 405690
Review URL: https://codereview.chromium.org/
576313002
Cr-Commit-Position: refs/heads/master@{#295626}