Move AudioMixer classes from transformer.audio to transformer package.

Transformer convention has been to avoid splitting into packages unless
necessary.

See https://jlbp.dev/JLBP-2: "Prefer fewer packages over more packages
to avoid unnecessarily publicizing internal details, since any
dependency across package boundaries needs to be public.

PiperOrigin-RevId: 503463294

libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixer.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import androidx.media3.common.audio.AudioProcessor.AudioFormat;
 import androidx.media3.common.audio.AudioProcessor.UnhandledAudioFormatException;

libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixerImpl.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import static androidx.media3.common.util.Assertions.checkArgument;
 import static androidx.media3.common.util.Assertions.checkNotNull;

libraries/transformer/src/main/java/androidx/media3/transformer/AudioMixingAlgorithm.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import android.annotation.SuppressLint;
 import androidx.media3.common.C;

libraries/transformer/src/main/java/androidx/media3/transformer/ChannelMixingMatrix.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import static androidx.media3.common.util.Assertions.checkArgument;
 

libraries/transformer/src/main/java/androidx/media3/transformer/FloatAudioMixingAlgorithm.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import static androidx.media3.common.util.Assertions.checkArgument;
 

libraries/transformer/src/main/java/androidx/media3/transformer/audio/package-info.java

@@ -1,19 +0,0 @@
-/*
- * Copyright 2022 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-@NonNullApi
-package androidx.media3.transformer.audio;
-
-import androidx.media3.common.util.NonNullApi;

libraries/transformer/src/test/java/androidx/media3/transformer/AudioMixerImplTest.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import static com.google.common.truth.Truth.assertThat;
 

libraries/transformer/src/test/java/androidx/media3/transformer/FloatAudioMixingAlgorithmTest.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package androidx.media3.transformer.audio;
+package androidx.media3.transformer;
 
 import static com.google.common.truth.Truth.assertThat;