[Android WebView] Enable Web Debugging in AW Test Shell

Android WebView Test Shell is a simple shell for testing WebView.
This patch enables remote web debugging for the shell.

R=joth@chromium.org

Review URL: https://codereview.chromium.org/25038004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225955 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225955