Bug 1281959 - Add a pref hiding the "Open with" option. r=dolske

If browser.download.forbid_open_with is set to true (default: false)
the download dialog will not ever show the "Open with" option for
opening the file with an external application; only the "Save" and
"Cancel" options will be available.

This is very useful to enable when the browser is sandboxed (e.g. via
AppArmor) in such a way that it is forbidden to run external
applications, since users then are not presented with this choice
which will not work and only cause confusion.

See https://trac.torproject.org/17502

modules/libpref/init/all.js

@@ -112,6 +112,9 @@ pref("offline-apps.quota.warn",        51200);
 // cache compression turned off for now - see bug #715198
 pref("browser.cache.compression_level", 0);
 
+// Don't show "Open with" option on download dialog if true.
+pref("browser.download.forbid_open_with", false);
+
 // Whether or not testing features are enabled.
 pref("dom.quotaManager.testing", false);
 

toolkit/mozapps/downloads/nsHelperAppDlg.js

@@ -472,7 +472,8 @@ nsUnknownContentTypeDialog.prototype = {
     var shouldntRememberChoice = (mimeType == "application/octet-stream" ||
                                   mimeType == "application/x-msdownload" ||
                                   this.mLauncher.targetFileIsExecutable);
-    if (shouldntRememberChoice && !this.openWithDefaultOK()) {
+    if ((shouldntRememberChoice && !this.openWithDefaultOK()) ||
+        Services.prefs.getBoolPref("browser.download.forbid_open_with")) {
       // hide featured choice
       this.dialogElement("normalBox").collapsed = true;
       // show basic choice