src/vs/workbench/services/keybinding/common/keybindingEditing.ts/KeybindingsEditingService/doResetKeybinding
class KeybindingsEditingService:	private doResetKeybinding(keybindingItem: ResolvedKeybindingItem): Promise<void> {
		return this.resolveAndValidate()
			.then(reference => {
				const model = reference.object.textEditorModel;
				if (!keybindingItem.isDefault) {
					this.removeUserKeybinding(keybindingItem, model);
					this.removeUnassignedDefaultKeybinding(keybindingItem, model);
				}
				return this.save().finally(() => reference.dispose());
			});
	}