Align superclasses for multiple inheritence.

This fixes llvm.org/PR15179.

Before:
class ColorChooserMac : public content::ColorChooser,
    public content::WebContentsObserver {
};

After:
class ColorChooserMac : public content::ColorChooser,
                        public content::WebContentsObserver {
};

llvm-svn: 175147