Honor users volume settings after logout -> login

the alsa-default.conf is made to present new users with reasonable
levels for various audio controls.  In the case of master volume,
chrome stores the user's preferences.

Previously, those preferences weren't being honored as there was a
race between the audio mixer in cros and alsa-default.conf  This
change lets the audio defaults get set prior to chrome evaluating and
setting audio preferences for the user.

1. Login to ChromeOS device.
2. goto http://html5zombo.com
3. Reduce the device volume to 10% (inaudible but not muted)
4. Logout, make sure volume is still 10% and login back.
5. Verify the video sound. (Device volume is still set to 10%).

Reviewed-on: http://gerrit.chromium.org/gerrit/1767
Reviewed-by: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>
(cherry picked from commit 8a45ca3f8a30460a348d2837ad3a1d034c905464)

Change-Id: Ib6abc8c4bfddbdb86bf72921c40a426653133f96
Reviewed-on: http://gerrit.chromium.org/gerrit/1772
Reviewed-by: Puneet Kumar <puneetster@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>
diff --git a/alsa-default.conf b/alsa-default.conf
index b8e9b2a..cba498f 100644
--- a/alsa-default.conf
+++ b/alsa-default.conf
@@ -6,8 +6,10 @@
 author          "chromium-os-dev@chromium.org"
 # On every user session, ensure the microphone is on and set at a
-# reasonable level.
-start on start-user-session
+# reasonable level.  Its a _task_ to ensure it completes prior to 
+# to CrOS setting users audio preferences
+start on starting start-user-session