Make sure calls to readBuffer() and readEmbeddedBuffer()
get the correct size, parent and offset passed in, so
these can be validated by libhwbinder.
Modified HwBlob to take a length argument as well,
so it can be validated.
Bug: 30498700
Test: hidl_test, hidl_test_java, Youtube, Maps, Netflix, Camera
Change-Id: I28712db97ae29b46acfe952d3d92d1ce5f666a4d
Merged-In: I28712db97ae29b46acfe952d3d92d1ce5f666a4d