From f05d85ff6bc57915f6945b3055933ccc8773ab59 Mon Sep 17 00:00:00 2001
From: Roy Tam <roytam@gmail.com>
Date: Sat, 8 Jun 2019 20:30:03 +0800
Subject: [PATCH] import change from mozilla upstream: Bug 1384330 - Blocking
 the mozAddonManager when pref
 'privacy.resistFingerprinting.block_mozAddonManager' is true.
 r=arthuredelstein,mossop

---
 toolkit/mozapps/webextensions/AddonManagerWebAPI.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/toolkit/mozapps/webextensions/AddonManagerWebAPI.cpp b/toolkit/mozapps/webextensions/AddonManagerWebAPI.cpp
index 3f2a7a5299..17ea9b0210 100644
--- a/toolkit/mozapps/webextensions/AddonManagerWebAPI.cpp
+++ b/toolkit/mozapps/webextensions/AddonManagerWebAPI.cpp
@@ -20,6 +20,12 @@ using namespace mozilla::dom;
 
 static bool
 IsValidHost(const nsACString& host) {
+  // This hidden pref allows users to disable mozAddonManager entirely if they want
+  // for fingerprinting resistance. Someone like Tor browser will use this pref.
+  if (Preferences::GetBool("privacy.resistFingerprinting.block_mozAddonManager")) {
+    return false;
+  }
+
   // This is ugly, but Preferences.h doesn't have support
   // for default prefs or locked prefs
   nsCOMPtr<nsIPrefService> prefService (do_GetService(NS_PREFSERVICE_CONTRACTID));