--- a/services/sync/modules/SyncedTabs.jsm
+++ b/services/sync/modules/SyncedTabs.jsm
@@ -204,16 +204,19 @@ let SyncedTabsInternal = {
       return true;
     }
 
     let engine = Weave.Service.engineManager.get("tabs");
     return engine && engine.enabled;
   },
 
   get hasSyncedThisSession() {
+    if (Weave.Service.hasSyncedThisSession) {
+      return true;
+    }
     let engine = Weave.Service.engineManager.get("tabs");
     return engine && engine.hasSyncedThisSession;
   },
 };
 
 Services.obs.addObserver(SyncedTabsInternal, "weave:engine:sync:finish");
 Services.obs.addObserver(SyncedTabsInternal, "weave:service:start-over");
 // Observe the pref the indicates the state of the tabs engine has changed.

--- a/services/sync/modules/service.js
+++ b/services/sync/modules/service.js
@@ -90,16 +90,22 @@ Sync11Service.prototype = {
   infoURL: null,
   storageURL: null,
   metaURL: null,
   cryptoKeyURL: null,
   // The cluster URL comes via the ClusterManager object, which in the FxA
   // world is ebbedded in the token returned from the token server.
   _clusterURL: null,
 
+  // A flag to indicate if we have synced in this session. This is to help
+  // consumers of remote tabs that may want to differentiate between "I've an
+  // empty tab list as I haven't yet synced" vs "I've an empty tab list
+  // as there really are no tabs"
+  hasSyncedThisSession: false,
+
   get clusterURL() {
     return this._clusterURL || "";
   },
   set clusterURL(value) {
     if (value != null && typeof value != "string") {
       throw new Error("cluster must be a string, got " + (typeof value));
     }
     this._clusterURL = value;
@@ -807,16 +813,17 @@ Sync11Service.prototype = {
     this.collectionKeys.clear();
     this.status.resetBackoff();
 
     // Reset Weave prefs.
     this._ignorePrefObserver = true;
     Svc.Prefs.resetBranch("");
     this._ignorePrefObserver = false;
     this.clusterURL = null;
+    this.hasSyncedThisSession = false;
 
     Svc.Prefs.set("lastversion", WEAVE_VERSION);
 
     this.identity.deleteSyncCredentials();
 
     try {
       this.identity.finalize();
       this.status.__authManager = null;
@@ -1109,16 +1116,17 @@ Sync11Service.prototype = {
     return this._lock("service.js: sync",
                       this._notify("sync", JSON.stringify({why}), async function onNotify() {
 
       let histogram = Services.telemetry.getHistogramById("WEAVE_START_COUNT");
       histogram.add(1);
 
       let synchronizer = new EngineSynchronizer(this);
       await synchronizer.sync(engineNamesToSync, why); // Might throw!
+      this.hasSyncedThisSession = true;
 
       histogram = Services.telemetry.getHistogramById("WEAVE_COMPLETE_SUCCESS_COUNT");
       histogram.add(1);
 
       // We successfully synchronized.
       // Check if the identity wants to pre-fetch a migration sentinel from
       // the server.
       // If we have no clusterURL, we are probably doing a node reassignment