Fixed chrome proxy via check

This prevents a crash when a token on the via header
is fewer than four characters.

BUG=349020

Review URL: https://codereview.chromium.org/187273002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255274 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255274
Add RenderThread::GetShutdownEvent().

This change adds RenderThread::GetShutdownEvent() to the public content API.
This is required for code outside of content/ that wants to safely use
interfaces like SyncChannel.

BUG=

Review URL: https://codereview.chromium.org/186973002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255275 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255275