audio: no notification sound when adjusting volume bar twice.

Notification sound won't take effect when the previous track hasn't
finished.
Need explicitly stop the previous ongoing track to alow the current one.

Change-Id: Ib344a8b14ecc47a5c8fdd9c11ae48a3541ea9a55
CRs-Fixed: 652236
Update Volume state for Unmounting Phase.

This change will update the state of volume
to "unmounting" when the volume is in Umounting Phase
It will prevent apps from getting wrong state when state
of volume is queried on receiving MEDIA_EJECT broadcast.

CRs-Fixed: 642047

Change-Id: Idce0569e076c9d64f2022e86ad995bc5428e2fbc
DocumentsUI: The title disappears after rotation

The onItemCheckedStateChanged() method in DirectoryFragment.java
called the setTitle() of ActionMode to modify the title of the
action bar. But this change is not redone after the activity is
recreated. Therefore, when the orientation is changed, the change
in title will be lost.

Set the android:configChanges for DocumentsActivity to avoid
recreating this activity.

CRs-Fixed: 641604

Change-Id: I768422b63a07fcb3ac2c8fa5c6007e49965ff713
DocumentsUI: Fix the issue of download status was displayed incompletely

The layout arrangement of date, size and summary are unreasonable.
Text was ellipsized when summary has too much characters.

Reconfigure "layout_weight" of date, size and summary can fix this
issue.

CRs-Fixed: 619201

Change-Id: I0c00d08d4793a38b80988378b4b510bdb3bf8720