src/vs/workbench/services/extensions/common/abstractExtensionService.ts/AbstractExtensionService/_onWillActivateExtension
class AbstractExtensionService:	public _onWillActivateExtension(extensionId: ExtensionIdentifier): void {
		this._extensionHostActiveExtensions.set(ExtensionIdentifier.toKey(extensionId), extensionId);
	}