Refine logic and add simple test for BatteryChartPreferenceController

Bug: 177406865
Test: make SettingsRoboTests
Test: make SettingsGoogleRoboTests
Change-Id: Ie218cf967c6f30c6eadcdfe6bfd3f37ccdc2276e

src/com/android/settings/fuelgauge/BatteryDiffEntry.java

@@ -200,7 +200,7 @@ public final class BatteryDiffEntry {
 
         final BatteryEntry.NameAndIcon nameAndIcon =
             BatteryEntry.loadNameAndIcon(
-                mContext, uid, /*uid=*/ null, /*batteryEntry=*/ null,
+                mContext, uid, /*handler=*/ null, /*batteryEntry=*/ null,
                 packageName, mAppLabel, mAppIcon);
         // Clears BatteryEntry internal cache since we will have another one.
         BatteryEntry.clearUidCache();