Add and document .nomedia constant for MediaStore (Issue 6365)

Change-Id: Ic9c4a784187cd1264584992411916a5beeefd864

Author: kostmo

api/current.xml

@@ -117955,6 +117955,17 @@
  visibility="public"
 >
 </field>
+<field name="MEDIA_IGNORE_FILENAME"
+ type="java.lang.String"
+ transient="false"
+ volatile="false"
+ value="&quot;.nomedia&quot;"
+ static="true"
+ final="true"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</field>
 <field name="MEDIA_SCANNER_VOLUME"
  type="java.lang.String"
  transient="false"

core/java/android/provider/MediaStore.java

@@ -1695,4 +1695,12 @@ public static Uri getMediaScannerUri() {
      * Name of current volume being scanned by the media scanner.
      */
     public static final String MEDIA_SCANNER_VOLUME = "volume";
+
+    /**
+     * Name of the file signaling the media scanner to ignore media in the containing directory
+     * and its subdirectories. Developers should use this to avoid application graphics showing
+     * up in the Gallery and likewise prevent application sounds and music from showing up in
+     * the Music app.
+     */
+    public static final String MEDIA_IGNORE_FILENAME = ".nomedia";
 }