camera2 ndk: Allow nullptr for ACameraCaptureSession_captureCallbacks.onClosed.

Bug: 134680093

Test: AImageReaderVendorTest

Change-Id: I8d365b434c257e949496d9495d0fa31a18a2e068
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>
diff --git a/camera/ndk/impl/ACameraCaptureSession.cpp b/camera/ndk/impl/ACameraCaptureSession.cpp
index d6f1412..68db233 100644
--- a/camera/ndk/impl/ACameraCaptureSession.cpp
+++ b/camera/ndk/impl/ACameraCaptureSession.cpp
@@ -33,7 +33,9 @@
         dev->unlockDevice();
     }
     // Fire onClosed callback
-    (*mUserSessionCallback.onClosed)(mUserSessionCallback.context, this);
+    if (mUserSessionCallback.onClosed != nullptr) {
+        (*mUserSessionCallback.onClosed)(mUserSessionCallback.context, this);
+    }
     ALOGV("~ACameraCaptureSession: %p is deleted", this);
 }