Build infra to inject slice to PreferenceFragment

Reuse the PreferenceController and LayoutPreference however create
specific one for slice:
1. SlicePreference: container to inject slice view
2. SlicePreferenceController: handle updates for slice

Also add styles for it with default layout.

Bug: 120803703
Test: RunSettingsRoboTests

Change-Id: I6ab083ad57117e6198dcba37702a25213da78719

src/com/android/settings/slices/SlicePreferenceController.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2018 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.slices;
+
+import android.content.Context;
+import android.net.Uri;
+
+import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.Observer;
+import androidx.preference.PreferenceScreen;
+import androidx.slice.Slice;
+import androidx.slice.widget.SliceLiveData;
+import androidx.slice.widget.SliceView;
+
+import com.android.settings.core.BasePreferenceController;
+import com.android.settingslib.core.lifecycle.LifecycleObserver;
+import com.android.settingslib.core.lifecycle.events.OnStart;
+import com.android.settingslib.core.lifecycle.events.OnStop;
+
+/**
+ * Default {@link BasePreferenceController} for {@link SliceView}. It will take {@link Uri} for
+ * Slice and display what's inside this {@link Uri}
+ */
+public class SlicePreferenceController extends BasePreferenceController implements
+        LifecycleObserver, OnStart, OnStop, Observer<Slice> {
+    @VisibleForTesting
+    LiveData<Slice> mLiveData;
+    private SlicePreference mSlicePreference;
+    private Uri mUri;
+
+    public SlicePreferenceController(Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+
+        mSlicePreference = (SlicePreference) screen.findPreference(
+                getPreferenceKey());
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return mUri != null ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+    }
+
+    public void setSliceUri(Uri uri) {
+        mUri = uri;
+        mLiveData = SliceLiveData.fromUri(mContext, mUri);
+
+        //TODO(b/120803703): figure out why we need to remove observer first
+        mLiveData.removeObserver(this);
+    }
+
+    @Override
+    public void onStart() {
+        if (mLiveData != null) {
+            mLiveData.observeForever(this);
+        }
+    }
+
+    @Override
+    public void onStop() {
+        if (mLiveData != null) {
+            mLiveData.removeObserver(this);
+        }
+    }
+
+    @Override
+    public void onChanged(Slice slice) {
+        mSlicePreference.onSliceUpdated(slice);
+    }
+}