Let MediaSession store duck state instead of volume multiplier

content/browser/media/session/media_session_delegate_android.h

 // 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.
 
 #ifndef CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
@@ skipping 19 matching lines @@
   // Called when the Android system requests the MediaSession to be suspended.
   // Called by Java through JNI.
   void OnSuspend(JNIEnv* env,
                  const base::android::JavaParamRef<jobject>& obj,
                  jboolean temporary);
 
   // Called when the Android system requests the MediaSession to be resumed.
   // Called by Java through JNI.
   void OnResume(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj);
 
-  // Called when the Android system requests the MediaSession to duck.
+  // Called when the Android system requests the MediaSession to start ducking.
   // Called by Java through JNI.
-  void OnSetVolumeMultiplier(JNIEnv* env, jobject obj,
-                             jdouble volume_multiplier);
+  void OnStartDucking(JNIEnv* env, jobject obj);
 
-  // Called when the Android system requests the MediaSession to duck.
+  // Called when the Android system requests the MediaSession to stop ducking.
+  // Called by Java through JNI.
+  void OnStopDucking(JNIEnv* env, jobject obj);
+
+  // Record when the Android system requests the MediaSession to duck.
   // Called by Java through JNI.
   void RecordSessionDuck(JNIEnv* env,
                          const base::android::JavaParamRef<jobject> &obj);
 
  private:
   // Weak pointer because |this| is owned by |media_session_|.
   MediaSession* media_session_;
   base::android::ScopedJavaGlobalRef<jobject> j_media_session_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSessionDelegateAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_