code: func (b *Build) Banners() (result []Logo) {
  	var os, ver string
  	// A swarming dimension may have multiple values.  Eg.
  	// Linux, Ubuntu, Ubuntu-14.04.  We want the most specific one.
  	// The most specific one always comes last.
  	for _, dim := range b.GetInfra().GetSwarming().GetBotDimensions() {
  		if dim.Key != "os" {
  			continue
  		}
  		os = dim.Value
  		parts := strings.SplitN(os, "-", 2)
  		if len(parts) == 2 {
  			os = parts[0]
  			ver = parts[1]
  		}
  	}
  	var base LogoBase
  	switch os {
  	case "Ubuntu":
  		base = Ubuntu
  	case "Windows":
  		base = Windows
  	case "Mac":
  		base = OSX
  	case "Android":
  		base = Android
  	default:
  		return
  	}
  	return []Logo{{
  		LogoBase: base,
  		Subtitle: ver,
  		Count:    1,
  	}}
  }
docs: // Banner returns names of icons to display next to the build number.
  // Currently displayed:
  // * OS, as determined by swarming dimensions.
  // TODO(hinoka): For device builders, display device type, and number of devices.