Android: use SetProcessBackgrounded for process visibility.
This patch removes custom ContentViewCore logic that adjusts process
bindings, hooking up the cross-platform
ChildProcessLauncher::SetProcessBackgrounded call instead.
This aligns visibility management on Android with other platforms and
simplifies ContentViewCore, removing last bits of process (pid)
awarness from it.
BUG=325896
Review URL: https://codereview.chromium.org/
142023003
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@263242 0039d316-1c4b-4281-b951-d872f2087c98