shared_memory_abi: Remove unused function and update comment
The fragment size is not necessarily 4 bytes long since
6e516e800c31("protozero: Pack length fields for short nested messages"):
old implementations of tracing service do not seem to have a problem
with this.
Bug: 162206162
Change-Id: If1ebb22d3f1ef553af58933c8944063ccb9f02cf
Perfetto is a production-grade open-source stack for performance instrumentation and trace analysis. It offers services and libraries and for recording system-level and app-level traces, native + java heap profiling, a library for analyzing traces using SQL and a web-based UI to visualize and explore multi-GB traces.
See https://perfetto.dev/docs or the /docs/ directory for documentation.