* Adjust macOS 26 corner radius to 16
Reduce the rounded corner radius used on macOS 26 and later from 17 to 16. Updates GetCornerRadiusMetric for kRoundedCornersBorderRadiusAtWindowCorner in browser/ui/views/brave_layout_provider_mac.mm to better align with the intended macOS 26 visuals.
* Use RoundedCornersF for view shadows
Migrate ViewShadow from an int corner radius to gfx::RoundedCornersF so shadows can use per-corner radii and scale correctly. Update ViewShadow to accept rounded corner radii, paint using an SkRRect path, and add SetCornerRadii to update the shadow when radii change. Propagate the new API through BraveContentsViewUtil, BraveBrowserView, SidePanel, LocationBar, and PromotionButton, passing appropriate RoundedCornersF values and updating layer rounded corners. Remove the BraveLayoutProviderMac corner override and consolidate corner radius metrics in layout_provider.cc (with macOS 26 handling) so layout providers supply the intended radii.
* Remove BraveLayoutProviderMac and simplify layout
Remove mac-specific BraveLayoutProviderMac implementation and unify layout provider usage across platforms. Deleted brave_layout_provider_mac.h/.mm and removed their BUILD.gn entries; brave_layout_provider.cc now always constructs BraveLayoutProvider and drops the platform include/ifdef. Also simplify ViewShadow::SetCornerRadii by calling SchedulePaint unconditionally (removed redundant null check), and tweak a comment in layout_provider.cc about matching Brave Mac corner radius. These changes consolidate layout logic and reduce platform-specific code.
Agustín Ruiz
6baad9d998