PNaCl: Add a test to check pexe requests come with right request headers.

Followup to: https://codereview.chromium.org/25869003/

Component updater will be looking for a pexe load signal
before allowing OnDemand updates. Currently, we use a
request header as the signal. Add a test to check that
PNaCl pexe requests come with the right headers and do
not munge other headers (like Origin, when conditionally
using CORS).

BUG=107438
TEST= browser_tests --gtest_filter=*PnaclHeaderTest*
NOTRY=true
(already tried...)

Review URL: https://codereview.chromium.org/48033002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232738 0039d316-1c4b-4281-b951-d872f2087c98
Linux: Update sysroot script to pull new tarballs with libpcap.

BUG=312380
NOTRY=true
TBR=mmoss@chromium.org

Review URL: https://codereview.chromium.org/57773003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232739 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232738
SVN changes up to revision 232739