Camera2: Add onCaptureQueueEmpty callback

onCaptureQueueEmpty is called when the non-repeating request queue in
cameraservice becomes empty. Application can use this callback as a
trigger for a new request.

Test: testMultipleCapture in PerformanceTest.java

Bug: 29006447
Change-Id: Id21afd74381e0b70f924c6026025c91a8ffd5ee0
diff --git a/camera/ndk/impl/ACameraDevice.cpp b/camera/ndk/impl/ACameraDevice.cpp
index 7d78e2b..229b159 100644
--- a/camera/ndk/impl/ACameraDevice.cpp
+++ b/camera/ndk/impl/ACameraDevice.cpp
@@ -1347,6 +1347,12 @@
 }
 
 binder::Status
+CameraDevice::ServiceCallback::onRequestQueueEmpty() {
+    // onRequestQueueEmpty not yet implemented in NDK
+    return binder::Status::ok();
+}
+
+binder::Status
 CameraDevice::ServiceCallback::onRepeatingRequestError(int64_t lastFrameNumber) {
     binder::Status ret = binder::Status::ok();