Add onDrmSessionAcquired and onDrmSessionReleased callbacks.

To report DRM session metrics in the future as part of the listener, we need
a callback at the end of the drm session to get the final metric state.
For completion, the session acquired callback is also added.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=211328412

RELEASENOTES.md

@@ -136,6 +136,8 @@
 * Prevent potential issues when reporting events for multi-period media sources
   ([#4492](https://github.com/google/ExoPlayer/issues/4492) and
   [#4634](https://github.com/google/ExoPlayer/issues/4634)).
+* Add callbacks to `DefaultDrmSessionEventListener` and `AnalyticsListener` to
+  get notified of acquired and released DRM sessions.
 
 ### 2.8.4 ###
 

library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java

@@ -534,6 +534,14 @@ public class AnalyticsCollector
 
   // DefaultDrmSessionManager.EventListener implementation.
 
+  @Override
+  public final void onDrmSessionAcquired() {
+    EventTime eventTime = generateReadingMediaPeriodEventTime();
+    for (AnalyticsListener listener : listeners) {
+      listener.onDrmSessionAcquired(eventTime);
+    }
+  }
+
   @Override
   public final void onDrmKeysLoaded() {
     EventTime eventTime = generateReadingMediaPeriodEventTime();
@@ -566,6 +574,14 @@ public class AnalyticsCollector
     }
   }
 
+  @Override
+  public final void onDrmSessionReleased() {
+    EventTime eventTime = generateLastReportedPlayingMediaPeriodEventTime();
+    for (AnalyticsListener listener : listeners) {
+      listener.onDrmSessionReleased(eventTime);
+    }
+  }
+
   // Internal methods.
 
   /** Returns read-only set of registered listeners. */

library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java

@@ -450,6 +450,13 @@ public interface AnalyticsListener {
    */
   default void onRenderedFirstFrame(EventTime eventTime, Surface surface) {}
 
+  /**
+   * Called each time a drm session is acquired.
+   *
+   * @param eventTime The event time.
+   */
+  default void onDrmSessionAcquired(EventTime eventTime) {}
+
   /**
    * Called each time drm keys are loaded.
    *
@@ -479,4 +486,11 @@ public interface AnalyticsListener {
    * @param eventTime The event time.
    */
   default void onDrmKeysRemoved(EventTime eventTime) {}
+
+  /**
+   * Called each time a drm session is released.
+   *
+   * @param eventTime The event time.
+   */
+  default void onDrmSessionReleased(EventTime eventTime) {}
 }

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

@@ -184,6 +184,7 @@ import java.util.UUID;
       if (sessionId != null) {
         mediaDrm.closeSession(sessionId);
         sessionId = null;
+        eventDispatcher.dispatch(DefaultDrmSessionEventListener::onDrmSessionReleased);
       }
       return true;
     }
@@ -279,6 +280,7 @@ import java.util.UUID;
 
     try {
       sessionId = mediaDrm.openSession();
+      eventDispatcher.dispatch(DefaultDrmSessionEventListener::onDrmSessionAcquired);
       mediaCrypto = mediaDrm.createMediaCrypto(sessionId);
       state = STATE_OPENED;
       return true;

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

@@ -20,6 +20,9 @@ import com.google.android.exoplayer2.Player;
 /** Listener of {@link DefaultDrmSessionManager} events. */
 public interface DefaultDrmSessionEventListener {
 
+  /** Called each time a drm session is acquired. */
+  default void onDrmSessionAcquired() {}
+
   /** Called each time keys are loaded. */
   void onDrmKeysLoaded();
 
@@ -42,4 +45,7 @@ public interface DefaultDrmSessionEventListener {
 
   /** Called each time offline keys are removed. */
   void onDrmKeysRemoved();
+
+  /** Called each time a drm session is released. */
+  default void onDrmSessionReleased() {}
 }

library/core/src/main/java/com/google/android/exoplayer2/util/EventLogger.java

@@ -390,6 +390,11 @@ public class EventLogger implements AnalyticsListener {
     logd(eventTime, "downstreamFormatChanged", Format.toLogString(mediaLoadData.trackFormat));
   }
 
+  @Override
+  public void onDrmSessionAcquired(EventTime eventTime) {
+    logd(eventTime, "drmSessionAcquired");
+  }
+
   @Override
   public void onDrmSessionManagerError(EventTime eventTime, Exception e) {
     printInternalError(eventTime, "drmSessionManagerError", e);
@@ -410,6 +415,11 @@ public class EventLogger implements AnalyticsListener {
     logd(eventTime, "drmKeysLoaded");
   }
 
+  @Override
+  public void onDrmSessionReleased(EventTime eventTime) {
+    logd(eventTime, "drmSessionReleased");
+  }
+
   /**
    * Logs a debug message.
    *

library/core/src/test/java/com/google/android/exoplayer2/analytics/AnalyticsCollectorTest.java

@@ -101,6 +101,8 @@ public final class AnalyticsCollectorTest {
   private static final int EVENT_DRM_ERROR = 34;
   private static final int EVENT_DRM_KEYS_RESTORED = 35;
   private static final int EVENT_DRM_KEYS_REMOVED = 36;
+  private static final int EVENT_DRM_SESSION_ACQUIRED = 37;
+  private static final int EVENT_DRM_SESSION_RELEASED = 38;
 
   private static final int TIMEOUT_MS = 10000;
   private static final Timeline SINGLE_PERIOD_TIMELINE = new FakeTimeline(/* windowCount= */ 1);
@@ -1091,6 +1093,11 @@ public final class AnalyticsCollectorTest {
       reportedEvents.add(new ReportedEvent(EVENT_RENDERED_FIRST_FRAME, eventTime));
     }
 
+    @Override
+    public void onDrmSessionAcquired(EventTime eventTime) {
+      reportedEvents.add(new ReportedEvent(EVENT_DRM_SESSION_ACQUIRED, eventTime));
+    }
+
     @Override
     public void onDrmKeysLoaded(EventTime eventTime) {
       reportedEvents.add(new ReportedEvent(EVENT_DRM_KEYS_LOADED, eventTime));
@@ -1111,6 +1118,11 @@ public final class AnalyticsCollectorTest {
       reportedEvents.add(new ReportedEvent(EVENT_DRM_KEYS_REMOVED, eventTime));
     }
 
+    @Override
+    public void onDrmSessionReleased(EventTime eventTime) {
+      reportedEvents.add(new ReportedEvent(EVENT_DRM_SESSION_RELEASED, eventTime));
+    }
+
     private static final class ReportedEvent {
 
       public final int eventType;