Import FML event loop

[xiaowei-guan]

As we konw, we created a new thread event loop for vsync waiter, I think we can use fml event loop instread of TCore, We do not necessarily need to use the EventLoop of the Tizen platform.

The advantage of importing FML event loop:

1. FML event loop is based on C++, easier to use.
2. EFL-related code can be deleted in advance.

The disadvantage is that FML-related code needs to be imported.

FML code path : https://github.com/flutter/flutter/tree/master/engine/src/flutter/fml

@JSUYA @seungsoo47 @gin7773 What do you think?

[JSUYA]

Wow, that would be great if it were possible.
It's actually not clear to me yet(at least) what to replace ecore and eina_thread_queue_* used for vsync_waiter.
I don't know much about fml, but from what I just briefly looked at, it looks like there are implementations for each platform. Do we need a Tizen implementation after all?

[xiaowei-guan]

Wow, that would be great if it were possible. It's actually not clear to me yet(at least) what to replace ecore and eina_thread_queue_* used for vsync_waiter. I don't know much about fml, but from what I just briefly looked at, it looks like there are implementations for each platform. Do we need a Tizen implementation after all?

No, we don't need add tizen specific code, we use platform/posix for FML

[JSUYA]

Wow, that would be great if it were possible. It's actually not clear to me yet(at least) what to replace ecore and eina_thread_queue_* used for vsync_waiter. I don't know much about fml, but from what I just briefly looked at, it looks like there are implementations for each platform. Do we need a Tizen implementation after all?

No, we don't need add tizen specific code, we use platform/posix for FML

If it's replaceable, I think it's a good idea. I'll also look into fml more.
+) If we encounter dependency issues on gn level(?) when importing fml code, I think we can use std::thread directly. (Just thinking about it...)

[xiaowei-guan]

Wow, that would be great if it were possible. It's actually not clear to me yet(at least) what to replace ecore and eina_thread_queue_* used for vsync_waiter. I don't know much about fml, but from what I just briefly looked at, it looks like there are implementations for each platform. Do we need a Tizen implementation after all?

No, we don't need add tizen specific code, we use platform/posix for FML

If it's replaceable, I think it's a good idea. I'll also look into fml more. +) If we encounter dependency issues on gn level(?) when importing fml code, I think we can use std::thread directly. (Just thinking about it...)

I tried to import FML message loop to embedder, as your side, I've encountered the following issues:

1. Too many files need to be imported.

2. FML some codes requires C++20.

It seems creating a new thread is the simplest solution.