Earlier quoted context omitted.
So extend the Web APIs to handle this. You don't have to do synchronous calls. Robert O'Callahan talked in that thread about the potential for extending the capabilities of Web Workers to allow the kind of things you want to do to be done asynchronously. I know I'd love to have the ability to render to a 2D or 3D canvas context in a Web Worker, for example (the kind of thing that sandboxed plugins want to do), but al…
PPAPI is a platform for plugins to safely port existing native code, and implement performance critical components. The PPAPI platform capabilities (audio, canvas, webgl, etc) already exist as regular JavaScript APIs in Chrome. So, if you want to use them on normal web content you can. However, in doing so you incur both the strengths and limitations of the web platform (e.g. JavaScript dispatch, IPC overhead, and a…
It requires no more engineering effort than it took to implement the corresponding code in the PPAPI, and probably a lot less. Moreover, non-NaCl and non-plugin code could benefit from it.
As explained before, what would need to be done is simply to expose native versions of the Web APIs. These APIs would mirror the Web APIs more or less exactly (maybe using pointers to buffers instead of typed arrays, for example, but otherwise they'd be the same). In the cases in which Web APIs are not sufficient, both the native and JavaScript versions would be extended. In this way, "performance critical components" of native code and Web content would both benefit.