Let MediaSession store duck state instead of volume multiplier

content/browser/media/session/media_session_delegate_android.cc

Index: content/browser/media/session/media_session_delegate_android.cc
diff --git a/content/browser/media/session/media_session_delegate_android.cc b/content/browser/media/session/media_session_delegate_android.cc
index 21bbaad8c3d502c7402b2fffdaa30cb9555a9b80..da826e9062a840816ff8770c706a0556c8f2f272 100644
--- a/content/browser/media/session/media_session_delegate_android.cc
+++ b/content/browser/media/session/media_session_delegate_android.cc
@@ -76,9 +76,12 @@ void MediaSessionDelegateAndroid::OnResume(
   media_session_->Resume(MediaSession::SuspendType::SYSTEM);
 }
 
-void MediaSessionDelegateAndroid::OnSetVolumeMultiplier(
-    JNIEnv*, jobject, jdouble volume_multiplier) {
-  media_session_->SetVolumeMultiplier(volume_multiplier);
+void MediaSessionDelegateAndroid::OnStartDucking(JNIEnv*, jobject) {
+  media_session_->StartDucking();
+}
+
+void MediaSessionDelegateAndroid::OnStopDucking(JNIEnv*, jobject) {
+  media_session_->StopDucking();
 }
 
 void MediaSessionDelegateAndroid::RecordSessionDuck(