https://www.washingtonpost.com has an EV-certificate, but it looks like OV (no name next to the padlock) in Opera on Ubuntu (not on Windows).
That is fixed in 44.0.2494.0, but https://twitter.com/ still looks like OV (same in Chrome 57). :|
LinuxSandboxing was updated 12 May. The new version of the document adds:
“The namespace sandbox aims to replace the setuid sandbox. It has the advantage of not requiring a setuid binary. It's based on (unprivileged) user namespaces in the Linux kernel. It generally requires a kernel >= 3.10, although it may work with 3.8 if certain patches are backported.
Starting with M-43, if the kernel supports it, unprivileged namespaces are used instead of the setuid sandbox. Starting with M-44, certain processes run in their own PID namespace, which isolates them better.”
So the answer is that SUID is disabled because the new Namespace Sandbox replaces it (if possible).
"/opt/google/chrome-beta/PepperFlash/libpepflashplayer.so" and "/opt/google/chrome-unstable/PepperFlash/libpepflashplayer.so" have been added to the list in 25.0.1606.0, “DNA-25302 [Linux] Add new pepper flash paths to configuration file”: http://blogs.opera.com/desktop/changelog-25/#b1606.0