Checkpoint of new storage UI.

Top-level storage UI now shows list of all devices, both internal
and adopted/private volumes, and public/shared volumes.

When viewing a private volume, show traditional clustering of data
types, including summary of other users.  For adopted volumes, any
actions are tucked away in a menu, since they're not primary.  Misc
files browsing is now provided by DocumentsUI.

Teach StorageMeasurement about new private volumes, including
handling emulated volumes stacked above them.  When measuring, only
consider apps actually hosted on the current volume UUID.

When viewing a public volume, we default to launching into file
management mode, and offer a simple eject button at the top-level
view.  File management mode is offered by new DocumentsUI browse
intent, and a Settings link there redirects back to us for actual
operations like ejecting/formatting.  When unmounted, we launch
into our action view.

Actions like ejecting/formatting just show simple toasts for now.

Bug: 19993667
Change-Id: Ie990ef3c01fb3717aaf8c79bfc53aac7edefdcf7

res/xml/device_info_storage_volume.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2008 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.
+-->
+
+<PreferenceScreen
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:settings="http://schemas.android.com/apk/res/com.android.settings"
+    android:title="@string/storage_settings"
+    settings:keywords="@string/keywords_storage">
+
+</PreferenceScreen>