Fix broken XML parsing idiom.

Code that expected a single top level element in an XML file
was doing something like :

while (type != START_TAG) { next(); }

This would loop forever when the XML being parsed was empty,
where each call to XmlPullParser.next() would return END_DOCUMENT.

bug: https://code.google.com/p/android/issues/detail?id=64173
Change-Id: I7543203e976a8999ae471a6c2d629249a87011bb
Update the color of the expandable volume panel icon

This still retains the old settings icon since it
happens to fit perfectly. Pressing it does indeed
show you a bunch of sliders like the icon indicates.

Also add xhdpi and xxhdpi versions.

Change-Id: I944a325c8871e1afc9d7163b0f23f7f9d8ae070a