android: Use new proxy from PROXY_CHANGE intent
When we get a PROXY_CHANGE intent, the intent comes with the new proxy value;
use this value instead of ignoring it and asking the system property store for
the new proxy. This fixes a race condition where the system property store may
not have the new proxy by the time we receive the intent.
BUG=none yet
TEST=trybot
Review URL: https://codereview.chromium.org/
26763005
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230208 0039d316-1c4b-4281-b951-d872f2087c98