The default Chrome PDF Viewer needs to have a way to define the Print Settings options that are set by Default. For example, there needs to be a Windows Registry/Group Policy method for defining whether or not PDF printing is set to "Fit to page" or not.
In a Windows environment this could easily be handled through the Registry/Group Policy by defining values in the:
(HKLM\HKCU)\Software\Policies\Google\Chrome
Similar to the the REG_DWORD DeveloperToolsDisabled you could define a value for controlling Chrome PDF Viewer Print Fit To Page setting.