Some gifs not being blocked

[FriarBroccoli]

GifJam is mostly working just fine, but recently I've started seeing animated gifs that are not blocked. Below are three examples. I assume it is because google (g+) is hiding the "gif" extensions, and since there is nothing obvious in their code to indicate it is a gif, there may be nothing you can do. Note that if you do a "save image as" you will see the gif extension.

https://lh6.googleusercontent.com/-zlw6I7nqXk0/VMQ8YcN401I/AAAAAAAAGEs/S8KrCJntKKE/w506-h357/2015%2B-%2B1

https://lh4.googleusercontent.com/-8l1gmaj91K0/VMN0p_mR8iI/AAAAAAAAWdU/GFf8mp6yyow/w426-h240/2015%2B-%2B1

https://lh3.googleusercontent.com/-tHudyazICgo/VMMHIYcCj9I/AAAAAAAAGC0/CQNn_7fTuEw/w346-h262-no/2015%2B-%2B1

Thanks for a great product.

[adamfur]

Chrome's webrequest pipeline doesn't currently allows any analysis of the content, besides looking at the supposed file extention.
I think the "save image as"-extention is figured out by looking at the content-type.