Start fleshing out new storage APIs.

Introduces new DocumentsContract which storage backends must
implement.  Backends surface a simple directory-like organizational
structure that enables a document to appear at multiple locations in
that hierarchy.  Querying a document or the contents of a directory
will return a Cursor populated with DocumentColumns, which includes
simple metadata.

Adds new OPEN_DOC and CREATE_DOC Intents, and permission to protect
storage backends.

Change-Id: Ib4984bc980182b2cedbe552908e5be94604ef085
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 83d6061..8ef127a 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1078,6 +1078,14 @@
         android:description="@string/permdesc_mediaStorageWrite"
         android:protectionLevel="signature|system" />
 
+    <!-- Allows an application to manage access to documents, usually as part
+         of a document picker. -->
+    <permission android:name="android.permission.MANAGE_DOCUMENTS"
+        android:permissionGroup="android.permission-group.STORAGE"
+        android:label="@string/permlab_manageDocs"
+        android:description="@string/permdesc_manageDocs"
+        android:protectionLevel="signature|system" />
+
     <!-- ================================== -->
     <!-- Permissions for screenlock         -->
     <!-- ================================== -->