Switching to another programming language is not easy, especially with a language like Rust in which you have to pick all kinds of tricks for binary compatibility with other programming languages. Additionally, you must of course have to retrain your programmers internally to use it efficiently (because a lot of security in Rust comes at the expense of performance, so you have to know what code you can and can’t use in many places).

In addition, Rust also has limitations, such as the sheer complexity you need to build binary trees that still work more efficiently in many algorithms. There aren’t many C libraries yet in sufficient maturity, so they have to be written by hand or you have to write links that leave the same vulnerabilities behind the C wall. For formats where the library actually defines the standard (there are at least two of them in the image field) the This takes several weeks.

Rust is a good language for this kind of thing, but it’s not the Holy Grail. However, there is already Tried rust in chrome, but even if everyone now puts in full time converting old C++ code to Rust, it would take months, if not years, to compile. Chromium has 34 million lines of code (part of it will probably be auto-generated), and you can’t just rewrite it.

Google prefers to make the existing C++ codebase more secure, saving them millions. This is also one of the reasons why they invest so much time and money in projects like puzzles, assemblers, and code analysis.