External texture segmentation fault

[barribarrier]

I found a segmentation fault in external texture.

I triggered a crash by playing and disposing video over and over again really fast. It eventually crashes.

flutter-embedded-linux/src/flutter/shell/platform/linux_embedded/external_texture_pixelbuffer.cc

Line 38 in 9dc1156

opengl_texture->name = state_->gl_texture;

gdb

Thread 9 "io.flutter.rast" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffdc4006c0 (LWP 154435)]
0x00005555555ee615 in flutter::ExternalTexturePixelBuffer::PopulateTexture (this=0x555555b98070, width=1280, height=720, 
    opengl_texture=0x7fffc01dd510)
    at /home/ubuntu/flutter-embedded-linux/src/flutter/shell/platform/linux_embedded/external_texture_pixelbuffer.cc:38
39        opengl_texture->name = state_->gl_texture;

This is because UnregisterTexture and PopulateTexture are called from a different thread.
It was fixed on upstream: flutter/engine#33688. I applied the changes in that PR to my local flutter-embedded-linux and I can confirm it no longer crashes.
I can create a PR based on this but it uses fml::closure.

[barribarrier]

I can confirm it no longer crashes

Well, it did crash on CopyPixelBuffer but I think its a separate issue. I might open a new issue for it later.

[barribarrier]

If implemented, I think this will require a proper thread synchronization in the pixelbuffer callback functions (copy_buffer_callback). Since it will now get called from a raster thread. video_player and camera