Add proguard keep rules for ExoPlayer.setVideoEffects

These symbols in `lib-effect` are referenced via reflection from
`CompositingVideoSinkProvider` in `lib-exoplayer` in order to avoid
a hard dependency from `lib-exoplayer` to `lib-effect`. Without this
keep rule, the symbols can get renamed by R8 resulting in the
invocations failing.

#minor-release

PiperOrigin-RevId: 601074636

libraries/exoplayer/proguard-rules.txt

@@ -61,3 +61,13 @@
 -keepclasseswithmembers class androidx.media3.exoplayer.rtsp.RtspMediaSource$Factory {
   <init>();
 }
+
+# Constructors and methods accessed via reflection in CompositingVideoSinkProvider
+-dontnote androidx.media3.effect.PreviewingSingleInputVideoGraph$Factory
+-keepclasseswithmembers class androidx.media3.effect.PreviewingSingleInputVideoGraph$Factory {
+  <init>(androidx.media3.common.VideoFrameProcessor$Factory);
+}
+-dontnote androidx.media3.effect.DefaultVideoFrameProcessor$Factory$Builder
+-keepclasseswithmembers class androidx.media3.effect.DefaultVideoFrameProcessor$Factory$Builder {
+  build();
+}

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/video/CompositingVideoSinkProvider.java

@@ -827,7 +827,6 @@ public final class CompositingVideoSinkProvider
             Suppliers.memoize(
                 () -> {
                   try {
-                    // TODO: b/284964524- Add LINT and proguard checks for media3.effect reflection.
                     Class<?> defaultVideoFrameProcessorFactoryBuilderClass =
                         Class.forName(
                             "androidx.media3.effect.DefaultVideoFrameProcessor$Factory$Builder");