Bug 1345857 - Clone TabData entries when restoring tabs, r=mikedeboer

MozReview-Commit-ID: BhAbhSHgXWt

browser/components/sessionstore/SessionStore.jsm

@@ -3570,7 +3570,9 @@ var SessionStoreInternal = {
 
     // Update the persistent tab state cache with |tabData| information.
     TabStateCache.update(browser, {
-      history: {entries: tabData.entries, index: tabData.index},
+      // NOTE: Copy the entries array shallowly, so as to not screw with the
+      // original tabData's history when getting history updates.
+      history: {entries: [...tabData.entries], index: tabData.index},
       scroll: tabData.scroll || null,
       storage: tabData.storage || null,
       formdata: tabData.formdata || null,

browser/components/sessionstore/TabState.jsm

@@ -179,7 +179,10 @@ var TabStateInternal = {
       }
 
       if (key === "history") {
-        tabData.entries = value.entries;
+        // Make a shallow copy of the entries array. We (currently) don't update
+        // entries in place, so we don't have to worry about performing a deep
+        // copy.
+        tabData.entries = [...value.entries];
 
         if (value.hasOwnProperty("userContextId")) {
           tabData.userContextId = value.userContextId;

browser/components/sessionstore/test/browser.ini

@@ -243,3 +243,4 @@ skip-if = !e10s # GroupedSHistory is e10s-only
 
 [browser_closed_objects_changed_notifications_tabs.js]
 [browser_closed_objects_changed_notifications_windows.js]
+[browser_duplicate_history.js]

browser/components/sessionstore/test/browser_duplicate_history.js

@@ -0,0 +1,22 @@
+XPCOMUtils.defineLazyModuleGetter(this, "SessionStore",
+  "resource:///modules/sessionstore/SessionStore.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "TabStateCache",
+  "resource:///modules/sessionstore/TabStateCache.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "TabStateFlusher",
+  "resource:///modules/sessionstore/TabStateFlusher.jsm");
+
+add_task(function* () {
+  yield BrowserTestUtils.withNewTab("http://example.com", function* (aBrowser) {
+    let tab = gBrowser.getTabForBrowser(aBrowser);
+    yield TabStateFlusher.flush(aBrowser);
+    let before = TabStateCache.get(aBrowser);
+
+    let newTab = SessionStore.duplicateTab(window, tab);
+    yield BrowserTestUtils.browserLoaded(newTab.linkedBrowser);
+    let after = TabStateCache.get(newTab.linkedBrowser);
+
+    isnot(before.history.entries, after.history.entries,
+          "The entry objects should not be shared");
+    yield BrowserTestUtils.removeTab(newTab);
+  });
+});