https://chromium-review.googlesource.com/c/chromium/src/+/668029/1 made that clearer, but even before that patch, the Context3DCB callback, used to get a context for WebMediaPlayerImpl::Paint and WebMediaPlayerImpl::CopyVideoTextureToPlatformTexture, binds the context at callback creation time (see https://cs.chromium.org/chromium/src/content/renderer/media/media_factory.cc?q=content/renderer/media/media_factory.cc&sq=package:chromium&l=211), not when the callback is called. This means the context is constant for the duration of WMPI, but it needs to be recreated after a GPU crash (which puts the context into "lost" state and it becomes non-functional), see https://cs.chromium.org/chromium/src/content/renderer/render_thread_impl.cc?type=cs&q=RenderThreadImpl::SharedMainThreadContextProvider&sq=package:chromium&l=1485