Fix nullness checker warnings

PiperOrigin-RevId: 310997932

library/common/src/main/java/com/google/android/exoplayer2/metadata/Metadata.java

@@ -63,8 +63,7 @@ public final class Metadata implements Parcelable {
    * @param entries The metadata entries.
    */
   public Metadata(List<? extends Entry> entries) {
-    this.entries = new Entry[entries.size()];
-    entries.toArray(this.entries);
+    this.entries = entries.toArray(new Entry[0]);
   }
 
   /* package */ Metadata(Parcel in) {

library/common/src/main/java/com/google/android/exoplayer2/metadata/id3/Id3Decoder.java

@@ -626,8 +626,7 @@ public final class Id3Decoder implements MetadataDecoder {
       }
     }
 
-    Id3Frame[] subFrameArray = new Id3Frame[subFrames.size()];
-    subFrames.toArray(subFrameArray);
+    Id3Frame[] subFrameArray = subFrames.toArray(new Id3Frame[0]);
     return new ChapterFrame(chapterId, startTime, endTime, startOffset, endOffset, subFrameArray);
   }
 
@@ -668,8 +667,7 @@ public final class Id3Decoder implements MetadataDecoder {
       }
     }
 
-    Id3Frame[] subFrameArray = new Id3Frame[subFrames.size()];
-    subFrames.toArray(subFrameArray);
+    Id3Frame[] subFrameArray = subFrames.toArray(new Id3Frame[0]);
     return new ChapterTocFrame(elementId, isRoot, isOrdered, children, subFrameArray);
   }