Oh my goodness! Google Classroom now has a student polling feature embedded within the "Question" feature. You have several options for this feature when you choose to add a Question to your stream. The question can be a multiple choice question or short answer. You can also allow students to view each others responses or even edit their response.
Some ideas for the polling feature: quick exit ticket, feedback on a unit, guiding question for an intro to a lesson, feedback on whether or not students are on target for a project, and more.
Below is a screenshot for the entry window for a question:
On the teacher side of the question, you can view a quick chart of the student responses similar to what you see in Forms. It gives you a quick snapshot without having to create a form and posting the link in classroom.
If you want to read more about this new feature that was released today here's a link to the Google for Education Blog.