--- a/browser/components/sessionstore/src/SessionStore.jsm
+++ b/browser/components/sessionstore/src/SessionStore.jsm
@@ -314,16 +314,20 @@ let SessionStoreInternal = {
   _deferredInitialState: null,
 
   // A promise resolved once initialization is complete
   _promiseInitialization: Promise.defer(),
 
   // Whether session has been initialized
   _sessionInitialized: false,
 
+  // True if session store is disabled by multi-process browsing.
+  // See bug 516755.
+  _disabledForMultiProcess: false,
+
   // The original "sessionstore.resume_session_once" preference value before it
   // was modified by saveState.  saveState will set the
   // "sessionstore.resume_session_once" to true when the
   // the "sessionstore.resume_from_crash" preference is false (crash recovery
   // is disabled) so that pinned tabs will be restored in the case of a
   // crash.  This variable is used to restore the original value so the
   // previous session is not always restored when
   // "sessionstore.resume_from_crash" is true.
@@ -362,16 +366,18 @@ let SessionStoreInternal = {
       Services.obs.addObserver(this, aTopic, true);
     }, this);
 
     this._initPrefs();
 
     // Do pref migration before we store any values and start observing changes
     this._migratePrefs();
 
+    this._disabledForMultiProcess = this._prefBranch.getBoolPref("tabs.remote");
+
     // this pref is only read at startup, so no need to observe it
     this._sessionhistory_max_entries =
       this._prefBranch.getIntPref("sessionhistory.max_entries");
 
     this._restoreOnDemand =
       this._prefBranch.getBoolPref("sessionstore.restore_on_demand");
     this._prefBranch.addObserver("sessionstore.restore_on_demand", this, true);
 
@@ -586,16 +592,19 @@ let SessionStoreInternal = {
       this._prefBranch.clearUserPref("sessionstore.max_concurrent_tabs");
     }
   },
 
   /**
    * Handle notifications
    */
   observe: function ssi_observe(aSubject, aTopic, aData) {
+    if (this._disabledForMultiProcess)
+      return;
+
     switch (aTopic) {
       case "domwindowopened": // catch new windows
         this.onOpen(aSubject);
         break;
       case "domwindowclosed": // catch closed windows
         this.onClose(aSubject);
         break;
       case "quit-application-requested":
@@ -649,16 +658,19 @@ let SessionStoreInternal = {
   },
 
   /* ........ Window Event Handlers .............. */
 
   /**
    * Implement nsIDOMEventListener for handling various window and tab events
    */
   handleEvent: function ssi_handleEvent(aEvent) {
+    if (this._disabledForMultiProcess)
+      return;
+
     var win = aEvent.currentTarget.ownerDocument.defaultView;
     switch (aEvent.type) {
       case "load":
         // If __SS_restore_data is set, then we need to restore the document
         // (form data, scrolling, etc.). This will only happen when a tab is
         // first restored.
         let browser = aEvent.currentTarget;
         if (browser.__SS_restore_data)

--- a/toolkit/content/widgets/browser.xml
+++ b/toolkit/content/widgets/browser.xml
@@ -608,16 +608,20 @@
         </body>
       </method>
 
       <field name="pageReport">null</field>
 
       <property name="securityUI">
         <getter>
           <![CDATA[
+            // Bug 666809 - SecurityUI support for e10s
+            if (!this.docShell)
+              return null;
+
             if (!this.docShell.securityUI) {
               const SECUREBROWSERUI_CONTRACTID = "@mozilla.org/secure_browser_ui;1";
               if (!this.hasAttribute("disablesecurity") &&
                   SECUREBROWSERUI_CONTRACTID in Components.classes) {
                 var securityUI = Components.classes[SECUREBROWSERUI_CONTRACTID]
                                            .createInstance(Components.interfaces.nsISecureBrowserUI);
                 securityUI.init(this.contentWindow);
               }