Add ExoMediaDrm.Provider

Allows shared ownership of ExoMediaDrms. Shared ownership will
allow users to pre-create ExoMediaDrms in their apps, as opposed
to having the DrmSessionManager create the ExoMediaDrm.

Issue:#4721
PiperOrigin-RevId: 269305850

library/core/src/main/java/com/google/android/exoplayer2/drm/ExoMediaDrm.java

@@ -33,9 +33,20 @@
  */
 public interface ExoMediaDrm<T extends ExoMediaCrypto> {
 
-  /**
-   * @see MediaDrm#EVENT_KEY_REQUIRED
-   */
+  /** {@link ExoMediaDrm} instances provider. */
+  interface Provider<T extends ExoMediaCrypto> {
+
+    /**
+     * Returns an {@link ExoMediaDrm} instance with acquired ownership for the DRM scheme identified
+     * by the given UUID.
+     *
+     * <p>Each call to this method must have a corresponding call to {@link ExoMediaDrm#release()}
+     * to ensure correct resource management.
+     */
+    ExoMediaDrm<T> acquireExoMediaDrm(UUID uuid);
+  }
+
+  /** @see MediaDrm#EVENT_KEY_REQUIRED */
   @SuppressWarnings("InlinedApi")
   int EVENT_KEY_REQUIRED = MediaDrm.EVENT_KEY_REQUIRED;
   /**
@@ -235,6 +246,16 @@ byte[] provideKeyResponse(byte[] scope, byte[] response)
   Map<String, String> queryKeyStatus(byte[] sessionId);
 
   /**
+   * Acquires ownership over this instance, which must be released by calling {@link #release()}.
+   */
+  void acquire();
+
+  /**
+   * Releases ownership of this instance. If a call to this method causes this instance to have no
+   * acquired ownerships, releases the underlying resources.
+   *
+   * <p>Callers of this method must not make any further use of this instance.
+   *
    * @see MediaDrm#release()
    */
   void release();

library/core/src/main/java/com/google/android/exoplayer2/drm/FrameworkMediaDrm.java

@@ -185,6 +185,11 @@ public Map<String, String> queryKeyStatus(byte[] sessionId) {
     return mediaDrm.queryKeyStatus(sessionId);
   }
 
+  @Override
+  public void acquire() {
+    // TODO: Implement reference counting.
+  }
+
   @Override
   public void release() {
     mediaDrm.release();