Minor DefaultDrmSessionManager tweaks

PiperOrigin-RevId: 269574864

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

@@ -343,7 +343,8 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto>
 
   /**
    * Sets the mode, which determines the role of sessions acquired from the instance. This must be
-   * called before {@link #acquireSession(Looper, DrmInitData)} is called.
+   * called before {@link #acquireSession(Looper, DrmInitData)} or {@link
+   * #acquirePlaceholderSession(Looper)} is called.
    *
    * <p>By default, the mode is {@link #MODE_PLAYBACK} and a streaming license is requested when
    * required.
@@ -410,6 +411,7 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto>
   @Override
   @Nullable
   public DrmSession<T> acquirePlaceholderSession(Looper playbackLooper) {
+    assertExpectedPlaybackLooper(playbackLooper);
     if (!allowPlaceholderSessions || mediaDrm.getExoMediaCryptoType() == null) {
       return null;
     }
@@ -426,6 +428,7 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto>
 
   @Override
   public DrmSession<T> acquireSession(Looper playbackLooper, DrmInitData drmInitData) {
+    assertExpectedPlaybackLooper(playbackLooper);
     maybeCreateMediaDrmHandler(playbackLooper);
 
     List<SchemeData> schemeDatas = null;
@@ -461,34 +464,6 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto>
     return session;
   }
 
-  private DefaultDrmSession<T> createNewDefaultSession(
-      @Nullable List<SchemeData> schemeDatas, boolean isPlaceholderSession) {
-    return new DefaultDrmSession<>(
-        uuid,
-        mediaDrm,
-        /* provisioningManager= */ this,
-        /* releaseCallback= */ this::onSessionReleased,
-        schemeDatas,
-        mode,
-        isPlaceholderSession,
-        offlineLicenseKeySetId,
-        optionalKeyRequestParameters,
-        callback,
-        Assertions.checkNotNull(playbackLooper),
-        eventDispatcher,
-        loadErrorHandlingPolicy);
-  }
-
-  private void maybeCreateMediaDrmHandler(Looper playbackLooper) {
-    Assertions.checkState(this.playbackLooper == null || this.playbackLooper == playbackLooper);
-    if (sessions.isEmpty()) {
-      this.playbackLooper = playbackLooper;
-      if (mediaDrmHandler == null) {
-        mediaDrmHandler = new MediaDrmHandler(playbackLooper);
-      }
-    }
-  }
-
   @Override
   @Nullable
   public Class<T> getExoMediaCryptoType(DrmInitData drmInitData) {
@@ -528,6 +503,35 @@ public class DefaultDrmSessionManager<T extends ExoMediaCrypto>
 
   // Internal methods.
 
+  private void assertExpectedPlaybackLooper(Looper playbackLooper) {
+    Assertions.checkState(this.playbackLooper == null || this.playbackLooper == playbackLooper);
+    this.playbackLooper = playbackLooper;
+  }
+
+  private void maybeCreateMediaDrmHandler(Looper playbackLooper) {
+    if (mediaDrmHandler == null) {
+      mediaDrmHandler = new MediaDrmHandler(playbackLooper);
+    }
+  }
+
+  private DefaultDrmSession<T> createNewDefaultSession(
+      @Nullable List<SchemeData> schemeDatas, boolean isPlaceholderSession) {
+    return new DefaultDrmSession<>(
+        uuid,
+        mediaDrm,
+        /* provisioningManager= */ this,
+        /* releaseCallback= */ this::onSessionReleased,
+        schemeDatas,
+        mode,
+        isPlaceholderSession,
+        offlineLicenseKeySetId,
+        optionalKeyRequestParameters,
+        callback,
+        Assertions.checkNotNull(playbackLooper),
+        eventDispatcher,
+        loadErrorHandlingPolicy);
+  }
+
   private void onSessionReleased(DefaultDrmSession<T> drmSession) {
     sessions.remove(drmSession);
     if (placeholderDrmSession == drmSession) {

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

@@ -18,6 +18,7 @@ package com.google.android.exoplayer2.drm;
 import android.media.MediaDrmException;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
+import com.google.android.exoplayer2.util.Util;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -110,7 +111,7 @@ public final class DummyExoMediaDrm<T extends ExoMediaCrypto> implements ExoMedi
 
   @Override
   public byte[] getPropertyByteArray(String propertyName) {
-    return new byte[0];
+    return Util.EMPTY_BYTE_ARRAY;
   }
 
   @Override