Add a new developer options screen for shared data.

Add a new Storage section in the developer options menu which has a
new Shared Data preference. This preference screen shows all shared data
blobs on the device. There is also a new screen for each data blob which
shows all of the packages which currently have a leases on it. This
screen also has a button to delete the shared data blob.

Bug: 150626561
Test: make RunSettingsRoboTests ROBOTEST_FILTER=SharedDataPreferenceControllerTest
Test: manual (visual)
Change-Id: Id84a33dc7eeac493b2f81d3996ad24ee70557a07

src/com/android/settings/development/storage/SharedDataPreferenceController.java

@@ -0,0 +1,52 @@
+/*
+ * 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.
+ */
+
+package com.android.settings.development.storage;
+
+import android.app.blob.BlobStoreManager;
+import android.content.Context;
+
+import androidx.preference.Preference;
+
+import com.android.settingslib.development.DeveloperOptionsPreferenceController;
+
+public class SharedDataPreferenceController extends DeveloperOptionsPreferenceController {
+
+    private static final String SHARED_DATA = "shared_data";
+
+    private BlobStoreManager mBlobStoreManager;
+
+    public SharedDataPreferenceController(Context context) {
+        super(context);
+        mBlobStoreManager = (BlobStoreManager) context.getSystemService(BlobStoreManager.class);
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return SHARED_DATA;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return mBlobStoreManager != null;
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        preference.setEnabled(mBlobStoreManager != null);
+        // TODO: update summary to indicate why this preference isn't available
+    }
+}