Reduce scope of media-compat proguard rules.

Before this change media-compat proguard rules were affecting classes
outside of Android support library. This change narrows down the scope
to only classes in android.support.v4.media

Bug: 62371424
Test: None
Change-Id: I2be9e652bd0061fc8ccf5361569bbd61d27ffa25
diff --git a/media-compat/proguard-rules.pro b/media-compat/proguard-rules.pro
index 38a9966..416b2e8 100644
--- a/media-compat/proguard-rules.pro
+++ b/media-compat/proguard-rules.pro
@@ -13,6 +13,6 @@
 # limitations under the License.
 
 # Prevent Parcelable objects from being removed or renamed.
--keep class * implements android.os.Parcelable {
+-keep class android.support.v4.media.** implements android.os.Parcelable {
     public static final android.os.Parcelable$Creator *;
 }
\ No newline at end of file