DocumentsUI handles GET_CONTENT; hinting, errors.

Document browser now takes over all GET_CONTENT requests that request
openable Uris. It shows both storage backends and includes other apps
that respond to GET_CONTENT. Only grants transient read permissions.

Better guarding against throwing storage backends. Send sort order
and local-only hinting to backends.

Require that OPEN/CREATE_DOC users include openable category.

Bug: 10330112, 10329976, 10340741, 10331689, 10329971
Change-Id: Ieb8768a6d71201816046f4a4c48832061a313c28
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 84f89b4..760f99b 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -47,6 +47,7 @@
     <string name="root_type_service">Services</string>
     <string name="root_type_shortcut">Shortcuts</string>
     <string name="root_type_device">Devices</string>
+    <string name="root_type_apps">More apps</string>
 
     <string name="pref_advanced_devices">Display advanced devices</string>
     <string name="pref_file_size">Display file size</string>