Enforce the rule that the timestamp from timelapse video source monotically increases

Change-Id: Ie5ccb43e0192420300da58525ec52af7544e8e9e
diff --git a/media/libstagefright/CameraSourceTimeLapse.cpp b/media/libstagefright/CameraSourceTimeLapse.cpp
index 3689557..cc22574 100644
--- a/media/libstagefright/CameraSourceTimeLapse.cpp
+++ b/media/libstagefright/CameraSourceTimeLapse.cpp
@@ -486,7 +486,8 @@
             if (mForceRead) {
                 LOGV("dataCallbackTimestamp timelapse: forced read");
                 mForceRead = false;
-                *timestampUs = mLastFrameTimestampUs;
+                *timestampUs =
+                    mLastFrameTimestampUs + mTimeBetweenTimeLapseVideoFramesUs;
                 return false;
             }
         }