Add empty check for path in UsageGraph

If path is empty, skip method since there is nothing to draw.

Bug: 132728523
Test: RunSettingsRoboTests
Change-Id: I6fdb7c2f69d3d658c47b58c7304cfeb7d4010a46

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

@@ -288,7 +288,11 @@ public class UsageGraph extends View {
         canvas.drawPath(mPath, paint);
     }
 
-    private void drawFilledPath(Canvas canvas, SparseIntArray localPaths, Paint paint) {
+    @VisibleForTesting
+    void drawFilledPath(Canvas canvas, SparseIntArray localPaths, Paint paint) {
+        if (localPaths.size() == 0) {
+            return;
+        }
         mPath.reset();
         float lastStartX = localPaths.keyAt(0);
         mPath.moveTo(localPaths.keyAt(0), localPaths.valueAt(0));