Change AppPrefLoader from AsyncTask to AsyncLoader.

Showing the wifi data usage results in reaching the max number of
threads in the pool executor. Switching the loader implementation
from Async task to AsynLoader and use a single loader to get the
whole list of preferences instead of using a new task to create each
list element.

Change-Id: I0da19ca09031a7fa178970c192e12a99ab489145
Fix: 33820327
Test: make RunSettingsRoboTests

tests/robotests/src/com/android/settings/datausage/AppPrefLoaderTest.java

@@ -0,0 +1,93 @@
+/*
+ * 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.datausage;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.graphics.drawable.Drawable;
+import android.support.v7.preference.Preference;
+
+import android.util.ArraySet;
+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.Answers;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class AppPrefLoaderTest {
+
+    @Mock(answer = Answers.RETURNS_DEEP_STUBS)
+    private Context mContext;
+    @Mock
+    private PackageManager mPackageManager;
+
+    private AppPrefLoader mLoader;
+
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        final ArraySet<String> pkgs = new ArraySet<>();
+        pkgs.add("pkg0");
+        pkgs.add("pkg1");
+        mLoader =
+            new AppPrefLoader(RuntimeEnvironment.application, pkgs, mPackageManager);
+    }
+
+    @Test
+    public void loadInBackground_packageNotFound_shouldReturnEmptySet()
+            throws NameNotFoundException {
+        when(mPackageManager.getApplicationInfo(anyString(), anyInt()))
+            .thenThrow(new NameNotFoundException());
+
+        ArraySet<Preference> preferences = mLoader.loadInBackground();
+        assertThat(preferences).isEmpty();
+    }
+
+    @Test
+    public void loadInBackground_shouldReturnPreference() throws NameNotFoundException {
+        ApplicationInfo info = mock(ApplicationInfo.class);
+        when(mPackageManager.getApplicationInfo(anyString(), anyInt())).thenReturn(info);
+        final Drawable drawable = mock(Drawable.class);
+        final String label = "Label1";
+        when(info.loadIcon(mPackageManager)).thenReturn(drawable);
+        when(info.loadLabel(mPackageManager)).thenReturn(label);
+
+        Preference preference = mLoader.loadInBackground().valueAt(0);
+        assertThat(preference.getTitle()).isEqualTo(label);
+        assertThat(preference.getIcon()).isEqualTo(drawable);
+        assertThat(preference.isSelectable()).isFalse();
+    }
+
+}