Fix crash when clicking item in Battery screen

"last full charge/Screen usage since full charge" goes crash when
clicking on it. This is because The default behaviour for
PowerGaugePreference is to start detail page and the above two items
are PowerGaugePreference.

This cl set these two items as non-selectable.

Bug: 37080048
Test: make -j40 SettingsTest
Change-Id: Ide4e151dcd0b44fb795a5753c91f2197b2a24a56

res/xml/power_usage_summary.xml

@@ -30,11 +30,13 @@
 
         <com.android.settings.fuelgauge.PowerGaugePreference
             android:key="last_full_charge"
-            android:title="@string/battery_last_full_charge"/>
+            android:title="@string/battery_last_full_charge"
+            android:selectable="false"/>
 
         <com.android.settings.fuelgauge.PowerGaugePreference
             android:key="screen_usage"
-            android:title="@string/device_screen_usage"/>
+            android:title="@string/device_screen_usage"
+            android:selectable="false"/>
 
     </PreferenceCategory>
 

tests/app/src/com/android/settings/fuelgauge/PowerUsageSummaryUiTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2017 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.fuelgauge;
+
+import static android.support.test.InstrumentationRegistry.getTargetContext;
+import static android.support.test.espresso.Espresso.onData;
+import static android.support.test.espresso.Espresso.onView;
+import static android.support.test.espresso.action.ViewActions.click;
+import static android.support.test.espresso.intent.Intents.intended;
+import static android.support.test.espresso.intent.Intents.intending;
+import static android.support.test.espresso.intent.matcher.IntentMatchers.hasComponent;
+import static android.support.test.espresso.matcher.PreferenceMatchers.withKey;
+import static android.support.test.espresso.matcher.ViewMatchers.isDescendantOfA;
+import static android.support.test.espresso.matcher.ViewMatchers.withId;
+import static android.support.test.espresso.matcher.ViewMatchers.withText;
+
+import static org.hamcrest.Matchers.allOf;
+import static org.hamcrest.core.IsAnything.anything;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import android.app.Activity;
+import android.app.Instrumentation;
+import android.content.Context;
+import android.content.Intent;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import com.android.settings.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class PowerUsageSummaryUiTest {
+    private static final String BATTERY_INTENT = "android.intent.action.POWER_USAGE_SUMMARY";
+
+    @Before
+    public void SetUp() {
+        Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
+        instrumentation.startActivitySync(new Intent(BATTERY_INTENT));
+    }
+
+    @Test
+    public void testClickLastFullCharge_shouldNotCrash() {
+        onView(withText(R.string.battery_last_full_charge)).perform(click());
+    }
+
+    @Test
+    public void testClickScreenUsage_shouldNotCrash() {
+        onView(withText(R.string.device_screen_usage)).perform(click());
+    }
+
+}