Created a build target for files in media/public/

This new build target is explicitly listed in the packager/packager.gyp
file.

Change-Id: I49e68ea64ae9a9a30204a269a1af17744f9d25d7

packager/media/public/public.gyp

@@ -0,0 +1,23 @@
+# Copyright 2017 Google Inc. All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+{
+  'includes': [
+    '../../common.gypi',
+  ],
+  'targets': [
+    {
+      'target_name': 'public',
+      'type': '<(component)',
+      'sources': [
+        'ad_cue_generator_params.h',
+        'chunking_params.h',
+        'crypto_params.h',
+        'mp4_output_params.h',
+      ],
+    },
+  ],
+}

packager/packager.gyp

@@ -33,6 +33,7 @@
         'media/formats/webm/webm.gyp:webm',
         'media/formats/webvtt/webvtt.gyp:webvtt',
         'media/formats/wvm/wvm.gyp:wvm',
+        'media/public/public.gyp:public',
         'media/replicator/replicator.gyp:replicator',
         'media/trick_play/trick_play.gyp:trick_play',
         'mpd/mpd.gyp:mpd_builder',