Allow sysui-managed remote volume controllers.

- Relax restriction on audio service calls that assume the volume
  ui is systemui, allow calls from a blessed component app.
- Blessed component app service saved in secure settings.
- SystemUI mediates requests to replace the volume dialog, prompts
  the user on activation.
- Show a low pri ongoing notification when the volume dialog is
  being replaced, to allow user restoration at any time.
- Replace the controller management code in VolumeUI to use a
  ServiceMonitor, backed by the new blessed app component setting.
- Add proper zen-related noman client wrappers, make avail to the
  registered volume controller.
- Everything is still @hidden, no api impact.

Bug: 19260237
Change-Id: Ie1383f57659090318a7eda737fdad5b8f88737d4
diff --git a/packages/SystemUI/res/values/strings.xml b/packages/SystemUI/res/values/strings.xml
index 6afca8a..0420d35 100644
--- a/packages/SystemUI/res/values/strings.xml
+++ b/packages/SystemUI/res/values/strings.xml
@@ -932,4 +932,19 @@
 
     <!-- Hide quick settings tile confirmation button -->
     <string name="quick_settings_reset_confirmation_button">Hide</string>
+
+    <!-- VolumeUI activation dialog: warning message -->
+    <string name="volumeui_prompt_message"><xliff:g id="app_name" example="Volume Prototype 1">%1$s</xliff:g> wants to be the volume dialog.</string>
+
+    <!-- VolumeUI activation dialog: allow button label -->
+    <string name="volumeui_prompt_allow">Allow</string>
+
+    <!-- VolumeUI activation dialog: deny button label -->
+    <string name="volumeui_prompt_deny">Deny</string>
+
+    <!-- VolumeUI restoration notification: title -->
+    <string name="volumeui_notification_title"><xliff:g id="app_name" example="Volume Prototype 1">%1$s</xliff:g> is the volume dialog</string>
+
+    <!-- VolumeUI restoration notification: text -->
+    <string name="volumeui_notification_text">Touch to restore the original.</string>
 </resources>