Bug 707862 - Reset childCount on SHEntry when all children have been removed; r=smaug

browser/components/sessionstore/test/Makefile.in

@@ -160,6 +160,7 @@ _BROWSER_TEST_FILES = \
 	browser_687710_2.js \
 	browser_694378.js \
 	browser_705597.js \
+	browser_707862.js \
 	$(NULL)
 
 ifneq ($(OS_ARCH),Darwin)

browser/components/sessionstore/test/browser_707862.js

@@ -0,0 +1,56 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+let tabState = {
+  entries: [{url: "about:home", children: [{url: "about:mozilla"}]}]
+};
+
+function test() {
+  waitForExplicitFinish();
+
+  let tab = gBrowser.addTab("about:blank");
+  registerCleanupFunction(function () gBrowser.removeTab(tab));
+
+  let browser = tab.linkedBrowser;
+
+  whenBrowserLoaded(browser, function () {
+    ss.setTabState(tab, JSON.stringify(tabState));
+
+    let sessionHistory = browser.sessionHistory;
+    let entry = sessionHistory.getEntryAtIndex(0, false);
+
+    whenChildCount(entry, 1, function () {
+      whenChildCount(entry, 2, function () {
+        whenBrowserLoaded(browser, function () {
+          let sessionHistory = browser.sessionHistory;
+          let entry = sessionHistory.getEntryAtIndex(0, false);
+
+          whenChildCount(entry, 0, finish);
+        });
+
+        // reload the browser to deprecate the subframes
+        browser.reload();
+      });
+
+      // create a dynamic subframe
+      let doc = browser.contentDocument;
+      let iframe = doc.createElement("iframe");
+      iframe.setAttribute("src", "about:mozilla");
+      doc.body.appendChild(iframe);
+    });
+  });
+}
+
+function whenBrowserLoaded(aBrowser, aCallback) {
+  aBrowser.addEventListener("load", function onLoad() {
+    aBrowser.removeEventListener("load", onLoad, true);
+    executeSoon(aCallback);
+  }, true);
+}
+
+function whenChildCount(aEntry, aChildCount, aCallback) {
+  if (aEntry.childCount == aChildCount)
+    aCallback();
+  else
+    executeSoon(function () whenChildCount(aEntry, aChildCount, aCallback));
+}

docshell/shistory/src/nsSHEntry.cpp

@@ -655,8 +655,16 @@ nsSHEntry::RemoveChild(nsISHEntry * aChild)
       childRemoved = mChildren.ReplaceObjectAt(nsnull, index);
     }
   }
-  if (childRemoved)
+  if (childRemoved) {
     aChild->SetParent(nsnull);
+
+    // reduce the child count, i.e. remove empty children at the end
+    for (PRInt32 i = mChildren.Count() - 1; i >= 0 && !mChildren[i]; --i) {
+      if (!mChildren.RemoveObjectAt(i)) {
+        break;
+      }
+    }
+  }
   return NS_OK;
 }