However, to actually have the C++ compiler do inlining at compile time (LTO be damned), we have to put the definitions of inline functions into header files, wh

However, to actually have the C++ compiler do inlining at compile time (LTO be damned), we have to put the definitions of inline functions into header files, which greatly increases their size and processing time. I can't think of a component in a browser that would require inlined function calls in order to be performant. To really matter it would have to be many millions of calls per second. Moreover, because the C++ compiler needs to see full class definitions to, e.g., know the size of an object and its inheritance relationships, we have to put the main meat of every class definition into a header file! So let me suggest that you revisit those inlined function calls again. Once you start putting them into proper .cpp files and make use of forward declarations where possible the whole header dependency graph will probably simplify quite a bit. Don't even get me started on templates. Right. Don't use them unless there's no other way. Especially avoid for large-ish classes that do complicated stuff. If you can spare a couple CPU cycles (and most of the time you can) determine things at run-time instead of compile time. Of course all of this is theory, not taking into account practical matters like deadlines, code readability or developer turnover. Full disclosure: I worked at Google, but not on the Chrome team :)