AudioPolicyManager: update getDevicesForAttributes

Add forVolume parameter to enable special volume handling.
This is the first step to remove getDevicesForStream.

Test: volume changes; adb shell dumpsys audio
Bug: 219974551
Merged-In: If0886e6e885a06d927befadb02830cead421fabd
Change-Id: If0886e6e885a06d927befadb02830cead421fabd
diff --git a/services/audiopolicy/AudioPolicyInterface.h b/services/audiopolicy/AudioPolicyInterface.h
index 5b2b87e..0ccc963 100644
--- a/services/audiopolicy/AudioPolicyInterface.h
+++ b/services/audiopolicy/AudioPolicyInterface.h
@@ -215,7 +215,8 @@
 
     // retrieves the list of enabled output devices for the given audio attributes
     virtual status_t getDevicesForAttributes(const audio_attributes_t &attr,
-                                             AudioDeviceTypeAddrVector *devices) = 0;
+                                             AudioDeviceTypeAddrVector *devices,
+                                             bool forVolume) = 0;
 
     // Audio effect management
     virtual audio_io_handle_t getOutputForEffect(const effect_descriptor_t *desc) = 0;