Mojo: Add BindingsSupportImpl on top of HandleWatcher (take 2)

Mojo: Add BindingsSupportImpl on top of HandleWatcher (take 2)

Plumb MojoResult to the callback set on HandleWatcher. Revise BindingsSupport
interface to make the implementation on top of HandleWatcher trivial.

Originally reviewed at https://codereview.chromium.org/62773003/. Includes fix
to mojo.gyp to make libmojo_shell link against mojo_common_lib on Android.

R=sky@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=234408

[sky, 2013-11-11 23:52:43]

LGTM

[commit-bot: I haz the power, 2013-11-12 00:53:48]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/darin@chromium.org/69633002/1

[commit-bot: I haz the power, 2013-11-12 01:40:16]

Retried try job too often on linux_rel for step(s) nacl_integration
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[darin (slow to review), 2013-11-12 05:10:14]

Committed patchset #1 manually as r234408 (presubmit successful).