diff -up firefox-66.0.1/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp.mozilla-1540145 firefox-66.0.1/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
--- firefox-66.0.1/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp.mozilla-1540145	2019-03-22 06:06:07.000000000 +0100
+++ firefox-66.0.1/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp	2019-04-01 09:33:18.621166482 +0200
@@ -6,7 +6,6 @@
 #include "nsISystemProxySettings.h"
 #include "mozilla/ModuleUtils.h"
 #include "nsIServiceManager.h"
-#include "nsIGConfService.h"
 #include "nsIURI.h"
 #include "nsReadableUtils.h"
 #include "nsArrayUtils.h"
@@ -32,16 +31,10 @@ class nsUnixSystemProxySettings final :
  private:
   ~nsUnixSystemProxySettings() = default;
 
-  nsCOMPtr<nsIGConfService> mGConf;
-  nsCOMPtr<nsIGSettingsService> mGSettings;
+    nsCOMPtr<nsIGSettingsService> mGSettings;
   nsCOMPtr<nsIGSettingsCollection> mProxySettings;
   nsInterfaceHashtable<nsCStringHashKey, nsIGSettingsCollection>
       mSchemeProxySettings;
-  bool IsProxyMode(const char* aMode);
-  nsresult SetProxyResultFromGConf(const char* aKeyBase, const char* aType,
-                                   nsACString& aResult);
-  nsresult GetProxyFromGConf(const nsACString& aScheme, const nsACString& aHost,
-                             int32_t aPort, nsACString& aResult);
   nsresult GetProxyFromGSettings(const nsACString& aScheme,
                                  const nsACString& aHost, int32_t aPort,
                                  nsACString& aResult);
@@ -66,20 +59,10 @@ nsresult nsUnixSystemProxySettings::Init
         NS_LITERAL_CSTRING("org.gnome.system.proxy"),
         getter_AddRefs(mProxySettings));
   }
-  if (!mProxySettings) {
-    mGConf = do_GetService(NS_GCONFSERVICE_CONTRACTID);
-  }
 
   return NS_OK;
 }
 
-bool nsUnixSystemProxySettings::IsProxyMode(const char* aMode) {
-  nsAutoCString mode;
-  return NS_SUCCEEDED(mGConf->GetString(
-             NS_LITERAL_CSTRING("/system/proxy/mode"), mode)) &&
-         mode.EqualsASCII(aMode);
-}
-
 nsresult nsUnixSystemProxySettings::GetPACURI(nsACString& aResult) {
   if (mProxySettings) {
     nsCString proxyMode;
@@ -92,14 +75,8 @@ nsresult nsUnixSystemProxySettings::GetP
     }
     /* The org.gnome.system.proxy schema has been found, but auto mode is not
      * set. Don't try the GConf and return empty string. */
-    aResult.Truncate();
-    return NS_OK;
   }
 
-  if (mGConf && IsProxyMode("auto")) {
-    return mGConf->GetString(NS_LITERAL_CSTRING("/system/proxy/autoconfig_url"),
-                             aResult);
-  }
   // Return an empty string when auto mode is not set.
   aResult.Truncate();
   return NS_OK;
@@ -217,30 +194,6 @@ static nsresult GetProxyFromEnvironment(
   return NS_OK;
 }
 
-nsresult nsUnixSystemProxySettings::SetProxyResultFromGConf(
-    const char* aKeyBase, const char* aType, nsACString& aResult) {
-  nsAutoCString hostKey;
-  hostKey.AppendASCII(aKeyBase);
-  hostKey.AppendLiteral("host");
-  nsAutoCString host;
-  nsresult rv = mGConf->GetString(hostKey, host);
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (host.IsEmpty()) return NS_ERROR_FAILURE;
-
-  nsAutoCString portKey;
-  portKey.AppendASCII(aKeyBase);
-  portKey.AppendLiteral("port");
-  int32_t port;
-  rv = mGConf->GetInt(portKey, &port);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  /* When port is 0, proxy is not considered as enabled even if host is set. */
-  if (port == 0) return NS_ERROR_FAILURE;
-
-  SetProxyResult(aType, host, port, aResult);
-  return NS_OK;
-}
-
 nsresult nsUnixSystemProxySettings::SetProxyResultFromGSettings(
     const char* aKeyBase, const char* aType, nsACString& aResult) {
   nsDependentCString key(aKeyBase);
@@ -366,63 +319,6 @@ static bool HostIgnoredByProxy(const nsA
   return memcmp(&ignoreAddr, &hostAddr, sizeof(PRIPv6Addr)) == 0;
 }
 
-nsresult nsUnixSystemProxySettings::GetProxyFromGConf(const nsACString& aScheme,
-                                                      const nsACString& aHost,
-                                                      int32_t aPort,
-                                                      nsACString& aResult) {
-  bool masterProxySwitch = false;
-  mGConf->GetBool(NS_LITERAL_CSTRING("/system/http_proxy/use_http_proxy"),
-                  &masterProxySwitch);
-  // if no proxy is set in GConf return NS_ERROR_FAILURE
-  if (!(IsProxyMode("manual") || masterProxySwitch)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  nsCOMPtr<nsIArray> ignoreList;
-  if (NS_SUCCEEDED(mGConf->GetStringList(
-          NS_LITERAL_CSTRING("/system/http_proxy/ignore_hosts"),
-          getter_AddRefs(ignoreList))) &&
-      ignoreList) {
-    uint32_t len = 0;
-    ignoreList->GetLength(&len);
-    for (uint32_t i = 0; i < len; ++i) {
-      nsCOMPtr<nsISupportsString> str = do_QueryElementAt(ignoreList, i);
-      if (str) {
-        nsAutoString s;
-        if (NS_SUCCEEDED(str->GetData(s)) && !s.IsEmpty()) {
-          if (HostIgnoredByProxy(NS_ConvertUTF16toUTF8(s), aHost)) {
-            aResult.AppendLiteral("DIRECT");
-            return NS_OK;
-          }
-        }
-      }
-    }
-  }
-
-  bool useHttpProxyForAll = false;
-  // This setting sometimes doesn't exist, don't bail on failure
-  mGConf->GetBool(NS_LITERAL_CSTRING("/system/http_proxy/use_same_proxy"),
-                  &useHttpProxyForAll);
-
-  nsresult rv;
-  if (!useHttpProxyForAll) {
-    rv = SetProxyResultFromGConf("/system/proxy/socks_", "SOCKS", aResult);
-    if (NS_SUCCEEDED(rv)) return rv;
-  }
-
-  if (aScheme.LowerCaseEqualsLiteral("http") || useHttpProxyForAll) {
-    rv = SetProxyResultFromGConf("/system/http_proxy/", "PROXY", aResult);
-  } else if (aScheme.LowerCaseEqualsLiteral("https")) {
-    rv = SetProxyResultFromGConf("/system/proxy/secure_", "PROXY", aResult);
-  } else if (aScheme.LowerCaseEqualsLiteral("ftp")) {
-    rv = SetProxyResultFromGConf("/system/proxy/ftp_", "PROXY", aResult);
-  } else {
-    rv = NS_ERROR_FAILURE;
-  }
-
-  return rv;
-}
-
 nsresult nsUnixSystemProxySettings::GetProxyFromGSettings(
     const nsACString& aScheme, const nsACString& aHost, int32_t aPort,
     nsACString& aResult) {
@@ -494,7 +390,6 @@ nsresult nsUnixSystemProxySettings::GetP
     nsresult rv = GetProxyFromGSettings(aScheme, aHost, aPort, aResult);
     if (NS_SUCCEEDED(rv)) return rv;
   }
-  if (mGConf) return GetProxyFromGConf(aScheme, aHost, aPort, aResult);
 
   return GetProxyFromEnvironment(aScheme, aHost, aPort, aResult);
 }