refactor: have GetXdgAppId() return a std::optional<std::string> (#49318)

* refactor: GetXdgAppId() now returns std::optional<std::string>

* refactor: slightly simplify app.setDesktopName() ts calls

* refactor: add better documentation for dekstop-entry in XDG notifications

default_app/main.ts

@@ -110,11 +110,9 @@ async function loadApplicationPackage (packagePath: string) {
       } else if (packageJson.name) {
         app.name = packageJson.name;
       }
-      if (packageJson.desktopName) {
-        app.setDesktopName(packageJson.desktopName);
-      } else {
-        app.setDesktopName(`${app.name}.desktop`);
-      }
+
+      app.setDesktopName(packageJson.desktopName || `${app.name}.desktop`);
+
       // Set v8 flags, deliberately lazy load so that apps that do not use this
       // feature do not pay the price
       if (packageJson.v8Flags) {

lib/browser/init.ts

@@ -126,11 +126,7 @@ if (packageJson.productName != null) {
 }
 
 // Set application's desktop name.
-if (packageJson.desktopName != null) {
-  app.setDesktopName(packageJson.desktopName);
-} else {
-  app.setDesktopName(`${app.name}.desktop`);
-}
+app.setDesktopName(packageJson.desktopName || `${app.name}.desktop`);
 
 // Set v8 flags, deliberately lazy load so that apps that do not use this
 // feature do not pay the price

shell/browser/native_window_views.cc

@@ -290,7 +290,9 @@ NativeWindowViews::NativeWindowViews(const gin_helper::Dictionary& options,
   params.wm_class_name = base::ToLowerASCII(name);
   params.wm_class_class = name;
   // Set Wayland application ID.
-  params.wayland_app_id = platform_util::GetXdgAppId();
+  if (auto const app_id = platform_util::GetXdgAppId()) {
+    params.wayland_app_id = *app_id;
+  }
 
   auto* native_widget = new views::DesktopNativeWidgetAura(widget());
   params.native_widget = native_widget;

shell/browser/notifications/linux/libnotify_notification.cc

@@ -141,13 +141,15 @@ void LibnotifyNotification::Show(const NotificationOptions& options) {
         notification_, "x-canonical-append", g_variant_new_string("true"));
   }
 
-  // Send the desktop name to identify the application
-  // The desktop-entry is the part before the .desktop
-  std::string desktop_id = platform_util::GetXdgAppId();
-  if (!desktop_id.empty()) {
+  // https://specifications.freedesktop.org/notification/latest-single/#id-1.9.7
+  // This specifies the name of the desktop filename representing the
+  // calling program. This should be the same as the prefix used for the
+  // application's .desktop file. An example would be "rhythmbox" from
+  // "rhythmbox.desktop". This can be used by the daemon to retrieve the
+  // correct icon for the application, for logging purposes, etc.
+  if (const std::optional<std::string> name = platform_util::GetXdgAppId()) {
     GetLibNotifyLoader().notify_notification_set_hint(
-        notification_, "desktop-entry",
-        g_variant_new_string(desktop_id.c_str()));
+        notification_, "desktop-entry", g_variant_new_string(name->c_str()));
   }
 
   GetLibNotifyLoader().notify_notification_set_hint(

shell/common/platform_util.h

@@ -61,13 +61,16 @@ bool SetLoginItemEnabled(const std::string& type,
 #endif
 
 #if BUILDFLAG(IS_LINUX)
-// Returns a desktop name if available.
-// Unlike libgtkui, does *not* use "chromium-browser.desktop" as a fallback.
+// Returns a desktop name (e.g. 'myapp.desktop') if available.
+// Unlike libgtkui, this does *not* use "chromium-browser.desktop" as a
+// fallback.
+// https://specifications.freedesktop.org/desktop-entry/latest/file-naming.html
 std::optional<std::string> GetDesktopName();
 
-// The XDG application ID must match the name of the desktop entry file without
-// the .desktop extension.
-std::string GetXdgAppId();
+// Returns the app id (e.g. 'myapp') if available.
+// This is equivalent to the basename of `GetDesktopName()`.
+// https://developer.gnome.org/documentation/tutorials/application-id.html
+std::optional<std::string> GetXdgAppId();
 #endif
 
 }  // namespace platform_util

shell/common/platform_util_linux.cc

@@ -413,18 +413,16 @@ std::optional<std::string> GetDesktopName() {
   return base::Environment::Create()->GetVar("CHROME_DESKTOP");
 }
 
-std::string GetXdgAppId() {
-  if (std::optional<std::string> desktop_file_name = GetDesktopName()) {
-    constexpr std::string_view kDesktopExtension = ".desktop";
-    if (base::EndsWith(*desktop_file_name, kDesktopExtension,
-                       base::CompareCase::INSENSITIVE_ASCII)) {
-      desktop_file_name->resize(desktop_file_name->size() -
-                                kDesktopExtension.size());
-    }
-    return *desktop_file_name;
-  }
+std::optional<std::string> GetXdgAppId() {
+  auto name = GetDesktopName();
+  if (!name)
+    return {};
 
-  return "";
+  // remove '.desktop' file suffix, if present
+  if (std::string_view suffix = ".desktop"; name->ends_with(suffix))
+    name->resize(std::size(*name) - std::size(suffix));
+
+  return *name;
 }
 
 }  // namespace platform_util