Merge "Fix releaseBufferCallback null pointer dereference" into sc-dev

                // callback and a release buffer callback happening at the same time to avoid an

                // additional ipc call from the server.

                if (surfaceStats.previousBufferId) {

                    ReleaseBufferCallback callback =

                            popReleaseBufferCallbackLocked(surfaceStats.previousBufferId);

                    ReleaseBufferCallback callback;

                    {

                        std::scoped_lock<std::mutex> lock(mMutex);

                        callback = popReleaseBufferCallbackLocked(surfaceStats.previousBufferId);

                    }

                    if (callback) {

                        callback(surfaceStats.previousBufferId,

                                 surfaceStats.previousReleaseFence