Don't let untranslated "<unknown>" or "null" be displayed in Music.

Finally checking in an old fix (for bug 1785503 and bug 1785492)
that got bumped from Cupcake.
diff --git a/src/com/android/music/AlbumBrowserActivity.java b/src/com/android/music/AlbumBrowserActivity.java
index 5488504..0d6c150 100644
--- a/src/com/android/music/AlbumBrowserActivity.java
+++ b/src/com/android/music/AlbumBrowserActivity.java
@@ -241,7 +241,11 @@
         mCurrentAlbumName = mAlbumCursor.getString(mAlbumCursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ALBUM));
         mCurrentArtistNameForAlbum = mAlbumCursor.getString(
                 mAlbumCursor.getColumnIndexOrThrow(MediaStore.Audio.Albums.ARTIST));
-        menu.setHeaderTitle(mCurrentAlbumName);
+        if (mCurrentAlbumName == null || mCurrentAlbumName.equals(MediaFile.UNKNOWN_STRING)) {
+            menu.setHeaderTitle(getString(R.string.unknown_album_name));
+        } else {
+            menu.setHeaderTitle(mCurrentAlbumName);
+        }
     }
 
     @Override
diff --git a/src/com/android/music/ArtistAlbumBrowserActivity.java b/src/com/android/music/ArtistAlbumBrowserActivity.java
index c005d04..35bf54e 100644
--- a/src/com/android/music/ArtistAlbumBrowserActivity.java
+++ b/src/com/android/music/ArtistAlbumBrowserActivity.java
@@ -314,7 +314,11 @@
             mCurrentArtistId = mArtistCursor.getString(mArtistCursor.getColumnIndexOrThrow(MediaStore.Audio.Artists._ID));
             mCurrentArtistName = mArtistCursor.getString(mArtistCursor.getColumnIndexOrThrow(MediaStore.Audio.Artists.ARTIST));
             mCurrentAlbumId = null;
-            menu.setHeaderTitle(mCurrentArtistName);
+            if (mCurrentArtistName == null || mCurrentArtistName.equals(MediaFile.UNKNOWN_STRING)) {
+                menu.setHeaderTitle(getString(R.string.unknown_artist_name));
+            } else {
+                menu.setHeaderTitle(mCurrentArtistName);
+            }
             return;
         } else if (itemtype == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {
             if (cpos == -1) {
@@ -331,7 +335,11 @@
             mArtistCursor.moveToPosition(gpos);
             mCurrentArtistNameForAlbum = mArtistCursor.getString(
                     mArtistCursor.getColumnIndexOrThrow(MediaStore.Audio.Artists.ARTIST));
-            menu.setHeaderTitle(mCurrentAlbumName);
+            if (mCurrentAlbumName == null || mCurrentAlbumName.equals(MediaFile.UNKNOWN_STRING)) {
+                menu.setHeaderTitle(getString(R.string.unknown_album_name));
+            } else {
+                menu.setHeaderTitle(mCurrentAlbumName);
+            }
         }
     }