Revert "Revert "audiopolicy: moves Stream Volume Curves to Engine""

This reverts commit efdbe3bfeff7c150d99900fddca005d48048f188.

Test: make
diff --git a/services/audiopolicy/engine/interface/AudioPolicyManagerInterface.h b/services/audiopolicy/engine/interface/AudioPolicyManagerInterface.h
index 498cc3b..c9e9507 100644
--- a/services/audiopolicy/engine/interface/AudioPolicyManagerInterface.h
+++ b/services/audiopolicy/engine/interface/AudioPolicyManagerInterface.h
@@ -18,6 +18,7 @@
 
 #include <AudioPolicyManagerObserver.h>
 #include <media/AudioProductStrategy.h>
+#include <IVolumeCurves.h>
 #include <policy.h>
 #include <Volume.h>
 #include <HwModule.h>
@@ -234,6 +235,21 @@
      */
     virtual status_t listAudioProductStrategies(AudioProductStrategyVector &strategies) const = 0;
 
+    /**
+     * @brief getVolumeCurvesForAttributes retrieves the Volume Curves interface for the
+     *        requested Audio Attributes.
+     * @param attr to be considered
+     * @return IVolumeCurves interface pointer if found, nullptr otherwise
+     */
+    virtual IVolumeCurves *getVolumeCurvesForAttributes(const audio_attributes_t &attr) = 0;
+
+    /**
+     * @brief getVolumeCurvesForStreamType retrieves the Volume Curves interface for the stream
+     * @param stream to be considered
+     * @return IVolumeCurves interface pointer if found, nullptr otherwise
+     */
+    virtual IVolumeCurves *getVolumeCurvesForStreamType(audio_stream_type_t stream) = 0;
+
     virtual void dump(String8 *dst) const = 0;
 
 protected: