Add battery percentage switch to display settings

Test: mmma packages/apps/Settings/tests/robotests
Bug:32539932
Change-Id: I08c1d0f3b6cb8be7d1456268498356f7ed833e5c

res/values/strings.xml

@@ -4554,6 +4554,11 @@
     <!-- [CHAR_LIMIT=40] Battery saver: Value for automatic entry option: pct% battery -->
     <string name="battery_saver_turn_on_automatically_pct">at <xliff:g id="percent">%1$s</xliff:g> battery</string>
 
+    <!-- [CHAR_LIMIT=40] Battery percentage: Title -->
+    <string name="battery_percentage">Battery percentage</string>
+    <!-- [CHAR_LIMIT=NONE] Battery percentage: Description for preference -->
+    <string name="battery_percentage_description">Show battery percentage in status bar</string>
+
     <!-- Process Stats strings -->
     <skip />
 

res/xml/power_usage_summary.xml

@@ -34,6 +34,11 @@
             android:title="@string/battery_saver"
             android:fragment="com.android.settings.fuelgauge.BatterySaverSettings"/>
 
+        <SwitchPreference
+            android:key="battery_percentage"
+            android:title="@string/battery_percentage"
+            android:summary="@string/battery_percentage_description"/>
+
         <!-- Cross-listed item, if you change this, also change it in ia_display_settings.xml -->
         <SwitchPreference
             android:key="auto_brightness"

src/com/android/settings/display/BatteryPercentagePreferenceController.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.settings.display;
+
+import android.content.Context;
+import android.provider.Settings;
+import android.support.v7.preference.Preference;
+import android.support.v14.preference.SwitchPreference;
+
+import com.android.settings.core.PreferenceController;
+
+import static android.provider.Settings.System.SHOW_BATTERY_PERCENT;
+
+/**
+ * A controller to manage the switch for showing battery percentage in the status bar.
+ */
+
+public class BatteryPercentagePreferenceController extends PreferenceController
+        implements Preference.OnPreferenceChangeListener {
+
+    private static final String KEY_BATTERY_PERCENTAGE = "battery_percentage";
+
+    public BatteryPercentagePreferenceController(Context context) {
+        super(context);
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_BATTERY_PERCENTAGE;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        int setting = Settings.System.getInt(mContext.getContentResolver(),
+                SHOW_BATTERY_PERCENT, 0);
+
+        ((SwitchPreference) preference).setChecked(setting == 1);
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        boolean showPercentage = (Boolean) newValue;
+        Settings.System.putInt(mContext.getContentResolver(), SHOW_BATTERY_PERCENT,
+                showPercentage ? 1 : 0);
+        return true;
+    }
+}

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

@@ -56,6 +56,7 @@ import com.android.settings.core.PreferenceController;
 import com.android.settings.core.instrumentation.MetricsFeatureProvider;
 import com.android.settings.dashboard.SummaryLoader;
 import com.android.settings.display.AutoBrightnessPreferenceController;
+import com.android.settings.display.BatteryPercentagePreferenceController;
 import com.android.settings.display.TimeoutPreferenceController;
 import com.android.settings.overlay.FeatureFactory;
 import com.android.settings.search.BaseSearchIndexProvider;
@@ -185,6 +186,7 @@ public class PowerUsageSummary extends PowerUsageBase {
         controllers.add(new AutoBrightnessPreferenceController(context));
         controllers.add(new TimeoutPreferenceController(context));
         controllers.add(new BatterySaverController(context, getLifecycle()));
+        controllers.add(new BatteryPercentagePreferenceController(context));
         return controllers;
     }
 

tests/robotests/src/com/android/settings/display/BatteryPercentagePreferenceControllerTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.display;
+
+import static android.provider.Settings.System.SHOW_BATTERY_PERCENT;
+import static com.google.common.truth.Truth.assertThat;
+
+import android.content.Context;
+import android.provider.Settings;
+import com.android.settings.SettingsRobolectricTestRunner;
+import com.android.settings.TestConfig;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.annotation.Config;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class BatteryPercentagePreferenceControllerTest {
+    @Mock private Context mContext;
+    private BatteryPercentagePreferenceController mController;
+
+    @Before
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+        mController = new BatteryPercentagePreferenceController(mContext);
+    }
+
+    private int getPercentageSetting() {
+        return Settings.System.getInt(mContext.getContentResolver(), SHOW_BATTERY_PERCENT, 0);
+    }
+
+    @Test
+    public void testOnPreferenceChange_TurnOnPercentage_PercentageOn() {
+        mController.onPreferenceChange(null, true);
+        final int isOn = getPercentageSetting();
+        assertThat(isOn).isEqualTo(1);
+    }
+
+    @Test
+    public void testOnPreferenceChange_TurnOffPercentage_PercentageOff() {
+        mController.onPreferenceChange(null, false);
+        final int isOn = getPercentageSetting();
+        assertThat(isOn).isEqualTo(0);
+    }
+}