libaudiohal@aidl: Fix drain expectation

drain in IDLE or STANDBY is treated as success

BUG: 353460645

Test: play compress offload playback

Change-Id: I169d9f23fcacc9b7a614945d58c269f78e03a72e
diff --git a/media/libaudiohal/impl/StreamHalAidl.h b/media/libaudiohal/impl/StreamHalAidl.h
index 0587640..62a1737 100644
--- a/media/libaudiohal/impl/StreamHalAidl.h
+++ b/media/libaudiohal/impl/StreamHalAidl.h
@@ -220,6 +220,16 @@
         return mLastReply.state;
     }
 
+    bool isInDrainedState(
+            const ::aidl::android::hardware::audio::core::StreamDescriptor::State state) {
+        if (state == ::aidl::android::hardware::audio::core::StreamDescriptor::State::IDLE ||
+            state == ::aidl::android::hardware::audio::core::StreamDescriptor::State::STANDBY) {
+            // drain equivalent states
+            return true;
+        }
+        return false;
+    }
+
     status_t getLatency(uint32_t *latency);
 
     // Always returns non-negative values.