Audio policy: notify system_server of routing change

Callback into AudioPolicyClientInterface to notify of routing
update whenever output is re-evaluated.
Add native test to verify callback is invoked on device
(dis)connection and setForceUse.

Bug: 162448412
Test: atest AudioServiceHostTest#testPreferredDeviceRouting
Test: atest AudioServiceHostTest#testDevicesForAttributes
Test: atest audiopolicy_tests:AudioPolicyManagerTestDeviceConnection#RoutingUpdate
Change-Id: Ia1a985b996bf8f2f63e72c4110f62f65f9f42f21
diff --git a/services/audiopolicy/service/AudioPolicyClientImpl.cpp b/services/audiopolicy/service/AudioPolicyClientImpl.cpp
index 90b93e2..77b5200 100644
--- a/services/audiopolicy/service/AudioPolicyClientImpl.cpp
+++ b/services/audiopolicy/service/AudioPolicyClientImpl.cpp
@@ -266,6 +266,11 @@
     mAudioPolicyService->onAudioVolumeGroupChanged(group, flags);
 }
 
+void AudioPolicyService::AudioPolicyClient::onRoutingUpdated()
+{
+    mAudioPolicyService->onRoutingUpdated();
+}
+
 audio_unique_id_t AudioPolicyService::AudioPolicyClient::newAudioUniqueId(audio_unique_id_use_t use)
 {
     return AudioSystem::newAudioUniqueId(use);