Ensure raw resources are kept

R8 does constant folding, so we need to keep buildRawResourceUri
to ensure that resources passed to it are kept.

PiperOrigin-RevId: 286153875

RELEASENOTES.md

@@ -9,6 +9,8 @@
   ([6773](https://github.com/google/ExoPlayer/issues/6773)).
 * Suppress ProGuard warnings for compile-time `javax.annotation` package
   ([#6771](https://github.com/google/ExoPlayer/issues/6771)).
+* Fix proguard rules for R8 to ensure raw resources used with
+  `RawResourceDataSource` are kept.
 
 ### 2.11.0 (2019-12-11) ###
 

library/core/proguard-rules.txt

@@ -1,5 +1,10 @@
 # Proguard rules specific to the core module.
 
+# Constant folding for resource integers may mean that a resource passed to this method appears to be unused. Keep the method to prevent this from happening.
+-keep class com.google.android.exoplayer2.upstream.RawResourceDataSource {
+  public static android.net.Uri buildRawResourceUri(int);
+}
+
 # Constructors accessed via reflection in DefaultRenderersFactory
 -dontnote com.google.android.exoplayer2.ext.vp9.LibvpxVideoRenderer
 -keepclassmembers class com.google.android.exoplayer2.ext.vp9.LibvpxVideoRenderer {
@@ -69,5 +74,5 @@
 
 # Some members of this class are being accessed from native methods. Keep them unobfuscated.
 -keep class com.google.android.exoplayer2.ext.video.VideoDecoderOutputBuffer {
-    *;
+  *;
 }