Add privileged permission for reading the current wallpaper image

OEMs can therefore arrange factory-default access to have access prior
to setup or user interaction.

Bug: 30770233
Bug: 64029450
Test: manual

Change-Id: I2cb30721f2a64ef50275b711ca10ca571248504a
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index 5b0f8d5..267e5d5c 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -1984,6 +1984,15 @@
         android:description="@string/permdesc_setWallpaperHints"
         android:protectionLevel="normal" />
 
+    <!-- Allow the app to read the system wallpaper image without
+        holding the READ_EXTERNAL_STORAGE permission.
+        <p>Not for use by third-party applications.
+        @hide
+        @SystemApi
+    -->
+    <permission android:name="android.permission.READ_WALLPAPER_INTERNAL"
+        android:protectionLevel="signature|privileged" />
+
     <!-- ============================================ -->
     <!-- Permissions for changing the system clock -->
     <!-- ============================================ -->