* refactor: in FramelessView, move empty function decls to header
* refactor: in electron::api::WebContents, move empty function decls to header
* refactor: in electron::api::NativeWindow, move empty function decls to header
* refactor: in electron::OffScreenWebContentsView, move empty function decls to header
* refactor: in electron::OffScreenRenderWidgetHostView, move empty function decls to header
* refactor: in auto_updater::AutoUpdater, move empty function decls to header
* refactor: in electorn::api::FrameSubscriber, move empty function decls to header
* refactor: in electorn::api::SimpleURLLoaderWrapper, move empty function decls to header
* refactor: in electorn::InspectableWebContents, move empty function decls to header
* refactor: in electorn::OffScreenVideoConsumer, move empty function decls to header
* refactor: in electron::OffScreenWebContentsView, move empty function decls to header
* refactor: in electron::TrayIcon, move empty function decls to header
* refactor: in electron::ViewsDelegate, move empty function decls to header
* refactor: in electron::MediaCaptureDevicesDispatcher, move empty function decls to header
* refactor: in electron::UsbChooserContext::DeviceObserver, move empty function decls to header
* refactor: in electron::ProxyingWebSocket, move empty function decls to header
* refactor: in electron::Notification, move empty function decls to header
* refactor: in electron::PlatformNotificationService, move empty function decls to header
* Revert "refactor: in electron::PlatformNotificationService, move empty function decls to header"
This reverts commit 9103750d03b9ba1ceccba43d11dfdc2404ff6191.
* refactor: in electron::ElectronPDFDocumentHelperClient, move empty function decls to header
* refactor: in electron::api::SpellCheckClient, move empty function decls to header
* refactor: in electron::ElectronExtensionHostDelegate, move empty function decls to header
* refactor: in electron::PlatformNotificationService, move empty function decls to header
* refactor: in electron::NativeWindowViews, move empty function decls to header
* chore: move SetTouchBar() back to cc
* Revert "refactor: in auto_updater::AutoUpdater, move empty function decls to header"
This reverts commit c43d6862d32c74f63f82700a7546a732ac05ecb8.