Increase PNaCl streaming buffer size (chrome side).
Fewer URL downloader callbacks needed, and fewer SRPC
calls. Relatively speaking it's a drop in the bucket
though, so don't notice any difference on my workstation.
Can only see total instructions and branches go down
without cache misses going up (according to perf).
BUG=none
R=jfb@chromium.org, teravest@chromium.org
Review URL: https://codereview.chromium.org/
189873004
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256039 0039d316-1c4b-4281-b951-d872f2087c98