Record important battery usage event into SharedPreference for dump()

Fix: 268300677
Test: presubmit
Change-Id: If03106c265b984bc2608528bdf45386973e3a14f

src/com/android/settings/fuelgauge/batteryusage/BatteryUsageDataLoader.java

@@ -57,6 +57,10 @@ public final class BatteryUsageDataLoader {
         }
         final long elapsedTime = System.currentTimeMillis() - start;
         Log.d(TAG, String.format("getBatteryUsageStats() in %d/ms", elapsedTime));
+        if (isFullChargeStart) {
+            DatabaseUtils.recordDateTime(
+                    context, DatabaseUtils.KEY_LAST_LOAD_FULL_CHARGE_TIME);
+        }
 
         // Uploads the BatteryEntry data into database.
         DatabaseUtils.sendBatteryEntryData(