do not send traffic to localhost through proxy for android

Bug: 18736075

Cherry-pick https://codereview.chromium.org/796003002/.
Clean cherry-pick.

The proxy config service for android does not allow
one to configure an exception for localhost be made.
The implementation for Linux did allow this in:
   proxy_config_service_linux.cc
it just seems it was overlooked for android.

Instead of adding in the ability to configure
localhost as an exclusion, it makes more sense
to just force the exception; it seems silly to
send traffic for localhost through a proxy.

This patch addresses the following bug in android:
   https://code.google.com/p/android/issues/detail?id=37031

Change-Id: I3b654d45e9f534961cae9147374023ef597aa927
1 file changed