--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -8948,24 +8948,16 @@
     "kind": "boolean",
     "description": "Whether a browser window is set as an e10s window"
   },
   "E10S_BLOCKED_FROM_RUNNING": {
     "expires_in_version": "never",
     "kind": "boolean",
     "description": "Whether the e10s pref was set but it was blocked from running due to blacklisted conditions"
   },
-  "E10S_ADDONS_BLOCKER_RAN": {
-    "alert_emails": ["firefox-dev@mozilla.org"],
-    "expires_in_version": "49",
-    "kind": "flag",
-    "releaseChannelCollection": "opt-out",
-    "bug_numbers": [1248796],
-    "description": "Whether the code to block e10s for add-ons users was called"
-  },
   "BLOCKED_ON_PLUGIN_MODULE_INIT_MS": {
     "alert_emails": ["perf-telemetry-alerts@mozilla.com"],
     "expires_in_version": "never",
     "kind": "exponential",
     "high": 10000,
     "n_buckets": 20,
     "keyed": true,
     "description": "Time (ms) that the main thread has been blocked on LoadModule and NP_Initialize in PluginModuleParent"

--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -4888,19 +4888,16 @@ mozilla::BrowserTabsRemoteAutostart()
 
   gBrowserTabsRemoteStatus = status;
 
   mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_STATUS, status);
   if (prefEnabled) {
     mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_BLOCKED_FROM_RUNNING,
                                     !gBrowserTabsRemoteAutostart);
   }
-  if (Preferences::HasUserValue("extensions.e10sBlockedByAddons")) {
-    mozilla::Telemetry::Accumulate(mozilla::Telemetry::E10S_ADDONS_BLOCKER_RAN, true);
-  }
   return gBrowserTabsRemoteAutostart;
 }
 
 void
 SetupErrorHandling(const char* progname)
 {
 #ifdef XP_WIN
   /* On Windows XPSP3 and Windows Vista if DEP is configured off-by-default