Where is the call data ------seoSettings

public PageHeadBuilder(SeoSettings seoSettings, HttpContextBase httpContext)
        {
            this._seoSettings = seoSettings;
            this._titleParts = new List<string>();
            this._metaDescriptionParts = new List<string>();
            this._metaKeywordParts = new List<string>();
            this._scriptParts = new Dictionary<ResourceLocation, List<ScriptReferenceMeta>>();
            this._cssParts = new Dictionary<ResourceLocation, List<string>>();
            this._canonicalUrlParts = new List<string>();
            this._httpContext = httpContext;
        }

I go to function directly when I debugging, however, the seosettings is already be a settled value. i want to know where is it be numbered? I can not find it.and I found that call this in every page.