Make the WebKitThread object start the WebKit thread on construction (not lazily).

NOTE: It's very possible this will have a startup performance impact.  I'm going to watch the bots after committing.

TODO: Clean up shutdown logic that exists simply because we don't know whether or not we'll ever start the WebKit thread.

TEST=The WebKit thread gets spun up early in the initialization process.
BUG=24144

Review URL: http://codereview.chromium.org/405007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@32319 0039d316-1c4b-4281-b951-d872f2087c98
4 files changed