Avoid AAudioService->AAudioServiceInterface inheritence

This is required in order to prepare for divergence of
AAudioServiceInterface from BnAAudioService: if AAudioService
inherits from both, we would have method collisions as soon as we
change the signatures on one of the interfaces.

We achieve the same behavior with an adapter, which in this change is
completely trivial, but will be used as soon as the interfaces
actually diverge.

Bug: 160253486
Test: Manual testing using OboeTester
      Ran atest CtsNativeMediaAAudioTestCases
Change-Id: I0d3e41e2378f1e6ff9cbe37461682f7373f463f2
diff --git a/services/oboeservice/AAudioServiceEndpointPlay.cpp b/services/oboeservice/AAudioServiceEndpointPlay.cpp
index 08d2319..53cb70b 100644
--- a/services/oboeservice/AAudioServiceEndpointPlay.cpp
+++ b/services/oboeservice/AAudioServiceEndpointPlay.cpp
@@ -41,10 +41,9 @@
 
 #define BURSTS_PER_BUFFER_DEFAULT   2
 
-AAudioServiceEndpointPlay::AAudioServiceEndpointPlay(AAudioService &audioService)
-    : AAudioServiceEndpointShared(
-        (AudioStreamInternal *)(new AudioStreamInternalPlay(audioService, true))) {
-}
+AAudioServiceEndpointPlay::AAudioServiceEndpointPlay(AAudioService& audioService)
+        : AAudioServiceEndpointShared(
+                new AudioStreamInternalPlay(audioService.asAAudioServiceInterface(), true)) {}
 
 aaudio_result_t AAudioServiceEndpointPlay::open(const aaudio::AAudioStreamRequest &request) {
     aaudio_result_t result = AAudioServiceEndpointShared::open(request);