From f0ba7c168c484dde3918691de600cf7e0a327862 Mon Sep 17 00:00:00 2001
From: Tim Taubert <ttaubert@mozilla.com>
Date: Wed, 13 Nov 2013 12:43:27 +0100
Subject: [PATCH] Bug 938093 - Swap TabStateCache contents when docShells are
 swapped r=billm

From ca18aa2560b9380aa67ccfb6b90f4bbe8d38fc57 Mon Sep 17 00:00:00 2001
---
 .../sessionstore/src/SessionStore.jsm         |  1 +
 .../sessionstore/src/TabStateCache.jsm        | 43 +++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/browser/components/sessionstore/src/SessionStore.jsm b/browser/components/sessionstore/src/SessionStore.jsm
index 0d9b338e00f5..b41bfb4bd465 100644
--- a/browser/components/sessionstore/src/SessionStore.jsm
+++ b/browser/components/sessionstore/src/SessionStore.jsm
@@ -648,6 +648,7 @@ let SessionStoreInternal = {
         browser = aEvent.currentTarget;
         let otherBrowser = aEvent.detail;
         TabState.onSwapDocShells(browser, otherBrowser);
+        TabStateCache.onSwapDocShells(browser, otherBrowser);
         break;
       case "TabOpen":
         this.onTabAdd(win, aEvent.originalTarget);
diff --git a/browser/components/sessionstore/src/TabStateCache.jsm b/browser/components/sessionstore/src/TabStateCache.jsm
index 2fcab3594324..5f932055bae5 100644
--- a/browser/components/sessionstore/src/TabStateCache.jsm
+++ b/browser/components/sessionstore/src/TabStateCache.jsm
@@ -96,6 +96,18 @@ this.TabStateCache = Object.freeze({
     return TabStateCacheInternal.removeField(aKey, aField);
   },
 
+  /**
+   * Swap cached data for two given browsers.
+   *
+   * @param {xul:browser} browser
+   *        The first of the two browsers that swapped docShells.
+   * @param {xul:browser} otherBrowser
+   *        The second of the two browsers that swapped docShells.
+   */
+  onSwapDocShells: function(browser, otherBrowser) {
+    TabStateCacheInternal.onSwapDocShells(browser, otherBrowser);
+  },
+
   /**
    * Total number of cache hits during the session.
    */
@@ -213,6 +225,37 @@ let TabStateCacheInternal = {
     TabStateCacheTelemetry.recordAccess(!!data);
   },
 
+  /**
+   * Swap cached data for two given browsers.
+   *
+   * @param {xul:browser} browser
+   *        The first of the two browsers that swapped docShells.
+   * @param {xul:browser} otherBrowser
+   *        The second of the two browsers that swapped docShells.
+   */
+  onSwapDocShells: function(browser, otherBrowser) {
+    // Make sure that one or the other of these has cached data,
+    // and let it be |browser|.
+    if (!this._data.has(browser)) {
+      [browser, otherBrowser] = [otherBrowser, browser];
+      if (!this._data.has(browser)) {
+        return;
+      }
+    }
+
+    // At this point, |browser| is guaranteed to have cached data,
+    // although |otherBrowser| may not. Perform the swap.
+    let data = this._data.get(browser);
+    if (this._data.has(otherBrowser)) {
+      let otherData = this._data.get(otherBrowser);
+      this._data.set(browser, otherData);
+      this._data.set(otherBrowser, data);
+    } else {
+      this._data.set(otherBrowser, data);
+      this._data.delete(browser);
+    }
+  },
+
   _normalizeToBrowser: function(aKey) {
     let nodeName = aKey.localName;
     if (nodeName == "tab") {