structs not classes.

For some reason that I do not, ninja prefers:

struct Foo {
  Foo();

 private:
  void Blah();
};

Rather than

class Foo {
 public:
  Foo();

 private:
  void Blah();
};

This catches the last two usages of "class" in the code base.

Signed-off-by: Thiago Farina <tfarina@chromium.org>