Optimize battery optimize page control flow

- Post the setup logic into background and setup once only when leaving
 this page, this can improve the performance since we won't setup
 every time when switching preference

Bug: 195306545
Bug: 199892006
Test: make SettingsRoboTests
Change-Id: I1c3ee4673cf5cdba0abe39f208dfb1412082c579

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

@@ -282,6 +282,15 @@ public class AdvancedPowerUsageDetail extends DashboardFragment implements
         }
     }
 
+    @Override
+    public void onPause() {
+        super.onPause();
+        if (mEnableTriState) {
+            Log.d(TAG, "Leave with mode: " + getSelectedPreference());
+            mBatteryOptimizeUtils.setAppUsageState(getSelectedPreference());
+        }
+    }
+
     @Override
     public void onDestroy() {
         super.onDestroy();
@@ -490,6 +499,18 @@ public class AdvancedPowerUsageDetail extends DashboardFragment implements
         mOptimizationMode = mBatteryOptimizeUtils.getAppOptimizationMode();
     }
 
+    private int getSelectedPreference() {
+        if (mRestrictedPreference.isChecked()) {
+            return BatteryOptimizeUtils.MODE_RESTRICTED;
+        } else if (mUnrestrictedPreference.isChecked()) {
+            return BatteryOptimizeUtils.MODE_UNRESTRICTED;
+        } else if (mOptimizePreference.isChecked()) {
+            return BatteryOptimizeUtils.MODE_OPTIMIZED;
+        } else {
+            return BatteryOptimizeUtils.MODE_UNKNOWN;
+        }
+    }
+
     private CharSequence getAppActiveTime(Bundle bundle) {
         final long foregroundTimeMs = bundle.getLong(EXTRA_FOREGROUND_TIME);
         final long backgroundTimeMs = bundle.getLong(EXTRA_BACKGROUND_TIME);