Cleanup SendAutofillTypePredictionsToRenderer

Minor refactoring/code cleanup adding the check for Renderer to do an early return if the Renderer is not available.

BUG=

Review URL: https://codereview.chromium.org/176943007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255010 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255010