Let MediaSession store duck state instead of volume multiplier

content/browser/media/session/media_session_delegate_android.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/media/session/media_session_delegate_android.h"
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_android.h"
 #include "jni/MediaSessionDelegate_jni.h"
 
@@ skipping 58 matching lines @@
 }
 
 void MediaSessionDelegateAndroid::OnResume(
     JNIEnv*, const JavaParamRef<jobject>&) {
   if (!media_session_->IsReallySuspended())
     return;
 
   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(
     JNIEnv*, const JavaParamRef<jobject>&) {
   media_session_->RecordSessionDuck();
 }
 
 // static
 std::unique_ptr<MediaSessionDelegate> MediaSessionDelegate::Create(
     MediaSession* media_session) {
   MediaSessionDelegateAndroid* delegate =
       new MediaSessionDelegateAndroid(media_session);
   delegate->Initialize();
   return std::unique_ptr<MediaSessionDelegate>(delegate);
 }
 
 }  // namespace content