Merge "binder: RpcTransport: change to size_t." am: 176a33a2b4 am: cc00b4f938 am: 9c7441f58a

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1787187

Change-Id: Ibc9ade0e925a1486f42f57725a3b4df8a56a355c