Update libchromiumcontent to Chrome 31

* vendor/libchromiumcontent f484ce1...4252769 (1):
  > Merge pull request #32 from brightray/chrome-31
Update for changes to devtools in Chrome 31

browser/devtools_embedder_message_dispatcher.* came from
chrome/browser/devtools, and were modified just enough to compile within
brightray.
Update for changes to net::FileProtocolHandler in Chrome 31

I just copied the way that Chrome initializes this object.
Update for changes to content::CreatePersistentCookieStore in Chrome 31

I just copied how Chrome initializes this object.
Stop setting helper process names on OS X

See https://codereview.chromium.org/45253002.
Update for ui -> gfx moves in Chrome 31

See https://codereview.chromium.org/23769011.