Add getContentMetadata and applyContentMetadataMutations to Cache interface

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189186679

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/Cache.java

@@ -238,4 +238,23 @@ public interface Cache {
    *     com.google.android.exoplayer2.C#LENGTH_UNSET} otherwise.
    *     com.google.android.exoplayer2.C#LENGTH_UNSET} otherwise.
    */
    */
   long getContentLength(String key);
   long getContentLength(String key);
+
+  /**
+   * Applies {@code mutations} to the {@link ContentMetadata} for the given key. A new {@link
+   * CachedContent} is added if there isn't one already with the given key.
+   *
+   * @param key The cache key for the data.
+   * @param mutations Contains mutations to be applied to the metadata.
+   * @throws CacheException If an error is encountered.
+   */
+  void applyContentMetadataMutations(String key, ContentMetadataMutations mutations)
+      throws CacheException;
+
+  /**
+   * Returns a snapshot of the {@link ContentMetadata} for the given key.
+   *
+   * @param key The cache key for the data.
+   * @return A snapshot of the {@link ContentMetadata} for the given key.
+   */
+  ContentMetadata getContentMetadataSnapshot(String key);
 }
 }

library/core/src/main/java/com/google/android/exoplayer2/upstream/cache/SimpleCache.java

@@ -412,26 +412,14 @@ public final class SimpleCache implements Cache {
     return index.getContentLength(key);
     return index.getContentLength(key);
   }
   }
 
 
-  /**
-   * Applies {@code mutations} to the {@link ContentMetadata} for the given key. A new {@link
-   * CachedContent} is added if there isn't one already with the given key.
-   *
-   * @param key The cache key for the data.
-   * @param mutations Contains mutations to be applied to the metadata.
-   * @throws CacheException If an error is encountered.
-   */
+  @Override
   public void applyContentMetadataMutations(String key, ContentMetadataMutations mutations)
   public void applyContentMetadataMutations(String key, ContentMetadataMutations mutations)
       throws CacheException {
       throws CacheException {
     index.applyContentMetadataMutations(key, mutations);
     index.applyContentMetadataMutations(key, mutations);
     index.store();
     index.store();
   }
   }
 
 
-  /**
-   * Returns a snapshot of the {@link ContentMetadata} for the given key.
-   *
-   * @param key The cache key for the data.
-   * @return A snapshot of the {@link ContentMetadata} for the given key.
-   */
+  @Override
   public ContentMetadata getContentMetadataSnapshot(String key) {
   public ContentMetadata getContentMetadataSnapshot(String key) {
     return index.getContentMetadataSnapshot(key);
     return index.getContentMetadataSnapshot(key);
   }
   }