I am curious which IDE does Google use for C++ and Java development?
Google is not a single person. Probably lots of IDEs and tools are used there.
Developers in Google are allowed to pick whatever IDE they feel most comfortable in. They are even allowed to pick which OS they feel most comfortable in. So it ranges from anything from Vi to Emacs to NetBeans to Eclipse to Visual Studio.
Mehrdad is very correct that it is highly unlikely that they standardize on one IDE for each language. However, there is probably a popular one or two for each language.
A good way to tell is to look at the source code they release that would need an IDE plugin, and see what they support. I notice (regarding Java) IDEA from Intellij tends to get early plugin support, but that could just be selection bias (because that is what I use).
C++ people at Google work primarily on Linux. My understanding is that they tend to use command line tools and emacs as a matter of pride. That being said, more and more Linux users are making the transition to Eclipse now that the CDT is maturing.
As for Java programming, I think Eclipse is fairly standard.