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.h b/camera/ndk/impl/ACameraDevice.h
index 051462b..eb8028b 100644
--- a/camera/ndk/impl/ACameraDevice.h
+++ b/camera/ndk/impl/ACameraDevice.h
@@ -74,6 +74,7 @@
         binder::Status onResultReceived(const CameraMetadata& metadata,
                               const CaptureResultExtras& resultExtras) override;
         binder::Status onPrepared(int streamId) override;
+        binder::Status onRequestQueueEmpty() override;
         binder::Status onRepeatingRequestError(int64_t lastFrameNumber) override;
       private:
         const wp<CameraDevice> mDevice;