Use package from sipper if default is null

The BatteryEntry need a background thread to update the
package name and icon. However in InstalledAppDetails we
don't have this thread and it is unnecessary because we
already has the package name.

This cl:
1. Use the mPackageName from InstalledAppDetails directly in
BatteryEntry
2. Double check the defaultPackageName in AdvancedPowerUsageDetail,
use packageName from sipper if default is null

Bug: 64127162
Test: RunSettingsRoboTests

Change-Id: I5d21afca17f177817976758c28ed86b3a10e95eb
Merged-In: I5d21afca17f177817976758c28ed86b3a10e95eb

tests/robotests/src/com/android/settings/fuelgauge/AdvancedPowerUsageDetailTest.java

@@ -354,6 +354,18 @@ public class AdvancedPowerUsageDetailTest {
                 "0%");
     }
 
+    @Test
+    public void testStartBatteryDetailPage_defaultPackageNull_choseFromBatterySipper() {
+        mBatteryEntry.defaultPackageName = null;
+        mBatteryEntry.sipper.mPackages = PACKAGE_NAME;
+
+        AdvancedPowerUsageDetail.startBatteryDetailPage(mTestActivity, null, mBatteryStatsHelper, 0,
+                mBatteryEntry, USAGE_PERCENT, null);
+
+        assertThat(mBundle.getString(AdvancedPowerUsageDetail.EXTRA_PACKAGE_NAME)).isEqualTo(
+                PACKAGE_NAME[0]);
+    }
+
     @Test
     public void testInitPreference_hasCorrectSummary() {
         Bundle bundle = new Bundle(4);