Track in-flight requests

This allows for verification of callbacks, and will also be helpful
when implementing flush.

BUG: 31653306
TEST: unit tests pass, test program runs
Change-Id: Id43d6cb3c2b9ca4adc96fc08282f88e0b7b904e1
diff --git a/modules/camera/3_4/camera.h b/modules/camera/3_4/camera.h
index 255156f..f21d33f 100644
--- a/modules/camera/3_4/camera.h
+++ b/modules/camera/3_4/camera.h
@@ -26,6 +26,7 @@
 
 #include "capture_request.h"
 #include "metadata/metadata.h"
+#include "request_tracker.h"
 #include "stream.h"
 
 namespace default_camera_hal {
@@ -138,6 +139,8 @@
         int mNumStreams;
         // Standard camera settings templates
         std::unique_ptr<const android::CameraMetadata> mTemplates[CAMERA3_TEMPLATE_COUNT];
+        // Track in flight requests.
+        std::unique_ptr<RequestTracker> mInFlightTracker;
 };
 }  // namespace default_camera_hal