Writing this here cause it was one heck of an adventure to finally get Dawn built on Windows. It's unclear if things are truly built and whether or not there might be more issues to resolve, but for now, by following these instructions, you should be able to at the very least, get Dawn built, set things up properly without any compiler complaints, and with a slight tweak, get the samples up and running.
Note that Google has suggested that the current build system setup is not recommended for producing libraries to be included into your own projects, but there is the desire to include CMake build support for this purpose in the future.
As you might imagine, Dawn is stil being developed so things are bound to be broken. Hopefully things will smooth out as the project reaches it's first major milestone. I am just a casual hobyist so I have no idea as to the current progress but there is a mailing list you can keep up with [here](https://groups.google.com/forum/#!forum/dawn-g