Define new AudioControl HAL for automotive.

This provides a mechanism for Android to interact with a car's
audio subsystem.
It is a partial replacement for the deprecated AUDIO_* properties in VehicleHal.
It also provides control over fade/balance.

Bug: 31623564
Test: build for bat_land.  VTS tests in future CL.
Change-Id: I4344cce3a6aa9a28d1327bf4d16bd080c7fd3f50
diff --git a/automotive/audiocontrol/1.0/default/AudioControlCallback.cpp b/automotive/audiocontrol/1.0/default/AudioControlCallback.cpp
new file mode 100644
index 0000000..ea79cad
--- /dev/null
+++ b/automotive/audiocontrol/1.0/default/AudioControlCallback.cpp
@@ -0,0 +1,31 @@
+#include "AudioControlCallback.h"
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace audiocontrol {
+namespace V1_0 {
+namespace implementation {
+
+// Methods from ::android::hardware::automotive::audiocontrol::V1_0::IAudioControlCallback follow.
+Return<void> AudioControlCallback::suggestPausePlayers() {
+    // TODO implement in framework (this is called by the HAL implementation when needed)
+    return Void();
+}
+
+Return<void> AudioControlCallback::suggestStopPlayers() {
+    // TODO implement in framework (this is called by the HAL implementation when needed)
+    return Void();
+}
+
+Return<void> AudioControlCallback::resumePlayers() {
+    // TODO implement in framework (this is called by the HAL implementation when needed)
+    return Void();
+}
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace audiocontrol
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android