Add mDNS discovery to the Fletch compiler

Add mDNS discovery to the Fletch compiler

This adds the new command 'x-discover' which will discover devices with
the Fletch agent.

This also adds the option to run discovery when asked for the IP address
of a remote device.

R=wibling@google.com
BUG=

Committed: https://github.com/dart-lang/fletch/commit/bc29f6b4db3d299dd8aee26ce8a7f288176feffd

[Søren Gjesse, 2015-11-10 12:37:06]

On 2015/11/10 12:34:09, Søren Gjesse wrote:

For this to work on Mac OS the following CLs need to land:

https://codereview.chromium.org/1411063006/
https://codereview.chromium.org/1416833009/

[wibling, 2015-11-10 12:46:35]

lgtm

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/driver/...
File pkg/fletchc/lib/src/driver/developer.dart (right):

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/driver/...
pkg/fletchc/lib/src/driver/developer.dart:360: if (line.isEmpty) {
NIT: Perhaps trim the line to deal with a space being entered before hitting
enter.

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/verbs/x...
File pkg/fletchc/lib/src/verbs/x_discover_verb.dart (right):

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/verbs/x...
pkg/fletchc/lib/src/verbs/x_discover_verb.dart:5: library
fletchc.verbs.x_upgrade_verb;
NIT: x_upgrade -> x_discover

[Søren Gjesse, 2015-11-10 15:55:11]

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/driver/...
File pkg/fletchc/lib/src/driver/developer.dart (right):

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/driver/...
pkg/fletchc/lib/src/driver/developer.dart:360: if (line.isEmpty) {
On 2015/11/10 12:46:34, wibling wrote:
> NIT: Perhaps trim the line to deal with a space being entered before hitting
> enter.

It is already trimmed above.

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/verbs/x...
File pkg/fletchc/lib/src/verbs/x_discover_verb.dart (right):

https://codereview.chromium.org/1422853009/diff/1/pkg/fletchc/lib/src/verbs/x...
pkg/fletchc/lib/src/verbs/x_discover_verb.dart:5: library
fletchc.verbs.x_upgrade_verb;
On 2015/11/10 12:46:34, wibling wrote:
> NIT: x_upgrade -> x_discover

Done.

[Søren Gjesse, 2015-11-10 15:56:13]

Committed patchset #3 (id:40001) manually as
bc29f6b4db3d299dd8aee26ce8a7f288176feffd (presubmit successful).