Clear unused pointer field when sending across binder

Bug: 28377502
Change-Id: Iad5ebfb0a9ef89f09755bb332579dbd3534f9c98
diff --git a/media/libmediaplayerservice/MetadataRetrieverClient.cpp b/media/libmediaplayerservice/MetadataRetrieverClient.cpp
index a5a1fa5..f6acdf6 100644
--- a/media/libmediaplayerservice/MetadataRetrieverClient.cpp
+++ b/media/libmediaplayerservice/MetadataRetrieverClient.cpp
@@ -231,6 +231,7 @@
     ALOGV("rotation: %d", frameCopy->mRotationAngle);
     frameCopy->mData = (uint8_t *)frameCopy + sizeof(VideoFrame);
     memcpy(frameCopy->mData, frame->mData, frame->mSize);
+    frameCopy->mData = 0;
     delete frame;  // Fix memory leakage
     return mThumbnail;
 }