Start sandbox process early

This patch uses the warmUp mechanism to reduce TTFP.  When the
user starts to enter a URL or uses the menu, a new child process
connection is established immediately.  The new child process will
then start faster when the URL is entered or a bookmark is chosen.

Change-Id: I422617d0fd327603da55ad78736fbd6c85c9e6b3
2 files changed