Bug 1621913 Don't show the defaultBrowserBox in settings under flatpak; r=settings-reviewers,Gijs

Under Flatpak we cannot determine if the application is set as default handler
for http/https protocols and also the application cannot set the system defaults.
In order to avoid user confusion we hide the defaultBrowserBox which
under flatpak shows always: "Firefox is not your default browser" and the
"Make Default..." button does not make any change to the system.

Differential Revision: https://phabricator.services.mozilla.com/D170590

browser/components/preferences/main.js

@@ -1269,7 +1269,9 @@ var gMainPane = {
     if (AppConstants.HAVE_SHELL_SERVICE) {
       let shellSvc = getShellService();
       let defaultBrowserBox = document.getElementById("defaultBrowserBox");
-      if (!shellSvc) {
+      let isInFlatpak = gGIOService?.isRunningUnderFlatpak;
+      // Flatpak does not support setting nor detection of default browser
+      if (!shellSvc || isInFlatpak) {
         defaultBrowserBox.hidden = true;
         return;
       }
@@ -2454,11 +2456,8 @@ var gMainPane = {
       possibleAppMenuItems.push(menuItem);
     }
     // Add gio handlers
-    if (Cc["@mozilla.org/gio-service;1"]) {
-      let gIOSvc = Cc["@mozilla.org/gio-service;1"].getService(
-        Ci.nsIGIOService
-      );
-      var gioApps = gIOSvc.getAppsForURIScheme(handlerInfo.type);
+    if (gGIOService) {
+      var gioApps = gGIOService.getAppsForURIScheme(handlerInfo.type);
       let possibleHandlers = handlerInfo.possibleApplicationHandlers;
       for (let handler of gioApps.enumerate(Ci.nsIHandlerApp)) {
         // OS handler share the same name, it's most likely the same app, skipping...

browser/components/preferences/preferences.js

@@ -68,6 +68,17 @@ XPCOMUtils.defineLazyServiceGetters(this, {
   gMIMEService: ["@mozilla.org/mime;1", "nsIMIMEService"],
 });
 
+if (Cc["@mozilla.org/gio-service;1"]) {
+  XPCOMUtils.defineLazyServiceGetter(
+    this,
+    "gGIOService",
+    "@mozilla.org/gio-service;1",
+    "nsIGIOService"
+  );
+} else {
+  this.gGIOService = null;
+}
+
 ChromeUtils.defineESModuleGetters(this, {
   BrowserUtils: "resource://gre/modules/BrowserUtils.sys.mjs",
   ContextualIdentityService:

toolkit/system/gnome/nsGIOService.cpp

@@ -702,6 +702,11 @@ nsresult nsGIOService::LaunchFile(const nsACString& aPath) {
   return LaunchPath(aPath);
 }
 
+nsresult nsGIOService::GetIsRunningUnderFlatpak(bool* aResult) {
+  *aResult = mozilla::widget::IsRunningUnderFlatpak();
+  return NS_OK;
+}
+
 static nsresult RevealDirectory(nsIFile* aFile, bool aForce) {
   nsAutoCString path;
   if (bool isDir; NS_SUCCEEDED(aFile->IsDirectory(&isDir)) && isDir) {

xpcom/system/nsIGIOService.idl

@@ -75,6 +75,7 @@ interface nsIGIOService : nsISupports
   AUTF8String        getDescriptionForMimeType(in AUTF8String mimeType);
 
   /*** Misc. methods ***/
+  [infallible] readonly attribute boolean isRunningUnderFlatpak;
 
   /* Open the given URI in the default application */
   [noscript] void showURI(in nsIURI uri);