AudioFlinger: Control volume using Port ID

This CL migrates the volume management within AudioFlinger
from stream type to port ID.

It gives full power to AudioPolicy to compute the list of port
(so MmapThreads/Tracks) on which volume control is required.

It prevents from overwritting MUSIC stream type which is
the default for volume groups without associated stream type.

Bug: 317212590
Test: build & play audio
Test: atest audiopolicy_tests
Flag: com.android.media.audioserver.portid_volume_management

Change-Id: I4c9e8bb45660c9ceffcc0f4029b0617f9795ab3c
diff --git a/services/audioflinger/datapath/VolumePortInterface.h b/services/audioflinger/datapath/VolumePortInterface.h
new file mode 100644
index 0000000..fb1c463
--- /dev/null
+++ b/services/audioflinger/datapath/VolumePortInterface.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2024 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.
+ */
+
+#pragma once
+
+#include <system/audio.h>
+
+namespace android {
+
+class VolumePortInterface : public virtual RefBase {
+public:
+    virtual void setPortVolume(float volume) = 0;
+    virtual float getPortVolume() const = 0;
+};
+
+}  // namespace android