iconSize property
Diameter of a collapsed-window chrome glyph (×, expand, play/pause,
mute), in logical pixels. The collapsed window has no authored content
under its chrome (it is media-only), so unlike PipExpanded.iconSize
this has no safe-zone/layout coupling to keep in sync — purely cosmetic.
Default raised from the previous fixed 12 (_chromeIcon's old literal),
which read as too small against a real device.
Implementation
final double iconSize;