Iterate on data usage chart UI.

Switched to inflating chart views from XML, using attributes for
configuration.  Start using drawable assets for chart components
instead of manually painting.  Include hand-cut assets, and animate
between states when touched to invoke.

Clamp sweeps to valid chart ranges and prepare for sweep labels.

Bug: 4768483, 4598460
Change-Id: Ic660c35bec826eb5e3f6a1dde3cc04d8c437ef2b

src/com/android/settings/widget/InvertedChartAxis.java

@@ -53,6 +53,11 @@ public class InvertedChartAxis implements ChartAxis {
         return mWrapped.getLabel(value);
     }
 
+    /** {@inheritDoc} */
+    public CharSequence getShortLabel(long value) {
+        return mWrapped.getShortLabel(value);
+    }
+
     /** {@inheritDoc} */
     public float[] getTickPoints() {
         final float[] points = mWrapped.getTickPoints();