Add battery usage time summary to usage list item

Insert app foregound and background usage time information into the
preference item summary based on the different scenarios.

Bug: 177406865
Test: make SettingsRoboTests
Test: make SettingsGoogleRoboTests
Change-Id: I13ba357666adfb7b57f52ffae18d09aed8dd0773

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

@@ -210,12 +210,17 @@ public class BatteryDiffEntry {
                     packageManager.getApplicationInfo(packageName, /*no flags*/ 0);
                 if (appInfo != null) {
                     mAppLabel = packageManager.getApplicationLabel(appInfo).toString();
+                    mAppIcon = packageManager.getApplicationIcon(appInfo);
                 }
             } catch (NameNotFoundException e) {
                 Log.e(TAG, "failed to retrieve ApplicationInfo for: " + packageName);
                 mAppLabel = packageName;
             }
         }
+        // Early return if we found the app label and icon resource.
+        if (mAppLabel != null && mAppIcon != null) {
+            return;
+        }
 
         final int uid = (int) mBatteryHistEntry.mUid;
         final String[] packages = packageManager.getPackagesForUid(uid);