Extract footer preference as a widget lib

Currently, developer needs to import SettingsLib to use
footer preference. But the size of SettingsLib is too huge.

We extract the footer preference as a lib so that developer
only needs to import a small lib for using footer.

Test: Rebuilt apk, and see the footer preference
Fix: 173088235
Change-Id: I35ba99a49c7a13542d79f0340eecdbe9844102d0

packages/SettingsLib/Android.bp

@@ -54,6 +54,7 @@ java_defaults {
         "SettingsLibEmergencyNumber",
         "SettingsLibTopIntroPreference",
         "SettingsLibBannerMessagePreference",
+        "SettingsLibFooterPreference",
     ],
 }
 

packages/SettingsLib/FooterPreference/Android.bp

@@ -0,0 +1,13 @@
+android_library {
+    name: "SettingsLibFooterPreference",
+
+    srcs: ["src/**/*.java"],
+    resource_dirs: ["res"],
+
+    static_libs: [
+        "androidx.annotation_annotation",
+        "androidx.preference_preference",
+    ],
+    sdk_version: "system_current",
+    min_sdk_version: "21",
+}

packages/SettingsLib/FooterPreference/AndroidManifest.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright (C) 2020 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.
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.android.settingslib.widget">
+
+    <uses-sdk android:minSdkVersion="21" />
+
+</manifest>

packages/SettingsLib/FooterPreference/res/drawable/ic_info_outline_24.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
-  Copyright (C) 2019 The Android Open Source Project
+  Copyright (C) 2020 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.

packages/SettingsLib/FooterPreference/res/values/attrs.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2020 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.
+-->
+
+<resources>
+    <attr name="footerPreferenceStyle" format="reference" />
+</resources>

packages/SettingsLib/FooterPreference/src/com/android/settingslib/widget/FooterPreference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 The Android Open Source Project
+ * Copyright (C) 2020 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.
@@ -16,7 +16,6 @@
 
 package com.android.settingslib.widget;
 
-import android.annotation.StringRes;
 import android.content.Context;
 import android.text.TextUtils;
 import android.text.method.LinkMovementMethod;
@@ -24,20 +23,19 @@ import android.util.AttributeSet;
 import android.widget.TextView;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
 import androidx.core.content.res.TypedArrayUtils;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceViewHolder;
 
-import com.android.settingslib.R;
-
 /**
  * A custom preference acting as "footer" of a page. It has a field for icon and text. It is added
  * to screen as the last preference.
  */
 public class FooterPreference extends Preference {
 
-    static final int ORDER_FOOTER = Integer.MAX_VALUE - 1;
     public static final String KEY_FOOTER = "footer_preference";
+    static final int ORDER_FOOTER = Integer.MAX_VALUE - 1;
 
     public FooterPreference(Context context, AttributeSet attrs) {
         super(context, attrs, TypedArrayUtils.getAttr(

packages/SettingsLib/res/values/attrs.xml

@@ -46,8 +46,6 @@
     <attr name="wifi_signal" format="reference" />
     <attr name="wifi_friction" format="reference" />
 
-    <attr name="footerPreferenceStyle" format="reference" />
-
     <!-- Workaround for b/74248169. These are duplicates of attrs in AndroidX preferences. -->
     <attr name="preferenceStyle" format="reference" />
     <attr name="switchPreferenceStyle" format="reference" />