From c9a9de8c488d42f569487f72efe29c96f9d68697 Mon Sep 17 00:00:00 2001
From: Doug Thayer <dothayer@mozilla.com>
Date: Tue, 15 May 2018 09:29:16 -0700
Subject: [PATCH] Bug 1176019 - Clear cached layers on location change
 r=mconley

To avoid a flash of stale content in the event of a slow tab
switch, we need to make sure we remove a tab from the cache if
its location changes while it's in the background.

MozReview-Commit-ID: ElpoWhhjb0n

--HG--
extra : rebase_source : 615ebd1a57916e0fe2b8c062ab47ffe748397033
---
 browser/base/content/tabbrowser.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/browser/base/content/tabbrowser.js b/browser/base/content/tabbrowser.js
index 5493526e0660..23567f0817be 100644
--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -4673,6 +4673,14 @@ class TabProgressListener {
         gBrowser._unifiedComplete.registerOpenPage(aLocation, userContextId);
         this.mBrowser.registeredOpenURI = aLocation;
       }
+
+      if (this.mTab != gBrowser.selectedTab) {
+        let tabCacheIndex = gBrowser._tabLayerCache.indexOf(this.mTab);
+        if (tabCacheIndex != -1) {
+          gBrowser._tabLayerCache.splice(tabCacheIndex, 1);
+          gBrowser._getSwitcher().cleanUpTabAfterEviction(this.mTab);
+        }
+      }
     }
 
     if (!this.mBlank) {