Pass a ui::PaintContext from ui::Layer to layer delegates.

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index 874dce699a4a1cfd727fc5b731547b101a8e9e7a..efe1785b4812e8463364e7f1742bafe0eb6fae60 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -594,9 +594,9 @@ void BridgedNativeWidget::OnDidChangeFocus(View* focused_before,
 ////////////////////////////////////////////////////////////////////////////////
 // BridgedNativeWidget, LayerDelegate:
 
-void BridgedNativeWidget::OnPaintLayer(gfx::Canvas* canvas) {
+void BridgedNativeWidget::OnPaintLayer(const ui::PaintContext& context) {
   DCHECK(window_visible_);
-  native_widget_mac_->GetWidget()->OnNativeWidgetPaint(canvas);
+  native_widget_mac_->GetWidget()->OnNativeWidgetPaint(context);
 }
 
 void BridgedNativeWidget::OnDelegatedFrameDamage(