Do physics grad school look for an undergrad math degree? I am currently a second year. I'm thinking about going to condensed matter physics grad school, but I don't know what degree combination would be the best. Does physics + chemistry sound like a good choice? I saw that many people going to physics grad school have a math degree. But I already run out of class slots to be a math + physics double major. I'm also afraid that physics grad school would not appreciate a chemistry degree.

I do have an interest in math. But I somehow feel that the math for physicists/chemists(specifically physical chemists) is a little different from that for mathematicians. Does it mean that physicists/chemists just pick up math along the way in their own fields? Which means I don't need to major in math in order to do physics research in grad school?
This depends entirely on the type of physics you would like to pursue. If you would like to be a theorist, especially in general relativity or quantum field theory, you should learn lots of math, and you will find advanced classes in abstract algebra, topology, and differential geometry quite helpful. 

However, you say that you are interested in condensed matter. Certainly you will need lots of math, but it is mostly applied math, and you will be taught what you need to know in your graduate physics program. The admissions committee will look favorably upon any double major, but your statement of purpose in you application should speak to how your elective major has influenced how you think about physics, and helped you choose an area of specialty. You should also describe any cross disciplinary research you have done, as this will show that you know how to integrate ideas across fields and bring a new perspective to the department. You can do this with either math or chemistry as a double major, but it seems that chemistry is more closely related to your interests as a physicist, and a solid knowledge there will be beneficial in both graduate school and your career.