Bug 1789474 - Allow detached documents to be overwritten in accessible mapping. r=Jamie,geckoview-reviewers,owlish

Also assure that unregistering an accessible removes the right one and
doesn't confuse the attached document with the detached one.

Add stderr output to Accessible::DebugPrint in Android as well.

Differential Revision: https://phabricator.services.mozilla.com/D157528

Author: eeejay

accessible/android/SessionAccessibility.cpp

@@ -1008,6 +1008,17 @@ Accessible* SessionAccessibility::GetAccessibleByID(int32_t aID) const {
   return accessible;
 }
 
+#ifdef DEBUG
+static bool IsDetachedDoc(Accessible* aAccessible) {
+  if (!aAccessible->IsRemote() || !aAccessible->AsRemote()->IsDoc()) {
+    return false;
+  }
+
+  return !aAccessible->Parent() ||
+         aAccessible->Parent()->FirstChild() != aAccessible;
+}
+#endif
+
 void SessionAccessibility::RegisterAccessible(Accessible* aAccessible) {
   if (IPCAccessibilityActive()) {
     // Don't register accessible in content process.
@@ -1044,8 +1055,14 @@ void SessionAccessibility::RegisterAccessible(Accessible* aAccessible) {
   }
   AccessibleWrap::SetVirtualViewID(aAccessible, virtualViewID);
 
-  MOZ_ASSERT(!sessionAcc->mIDToAccessibleMap.Contains(virtualViewID),
-             "ID already registered");
+  Accessible* oldAcc = sessionAcc->mIDToAccessibleMap.Get(virtualViewID);
+  if (oldAcc) {
+    // About to overwrite mapping of registered accessible. This should
+    // only happen when the registered accessible is a detached document.
+    MOZ_ASSERT(IsDetachedDoc(oldAcc),
+               "ID already registered to non-detached document");
+  }
+
   sessionAcc->mIDToAccessibleMap.InsertOrUpdate(virtualViewID, aAccessible);
 }
 
@@ -1064,8 +1081,21 @@ void SessionAccessibility::UnregisterAccessible(Accessible* aAccessible) {
   RefPtr<SessionAccessibility> sessionAcc = GetInstanceFor(aAccessible);
   MOZ_ASSERT(sessionAcc, "Need SessionAccessibility to unregister Accessible!");
   if (sessionAcc) {
-    MOZ_ASSERT(sessionAcc->mIDToAccessibleMap.Contains(virtualViewID),
-               "Unregistering unregistered accessible");
+    Accessible* registeredAcc =
+        sessionAcc->mIDToAccessibleMap.Get(virtualViewID);
+    if (registeredAcc != aAccessible) {
+      // Attempting to unregister an accessible that is not mapped to
+      // its virtual view ID. This probably means it is a detached document
+      // and a more recent document overwrote its '-1' mapping.
+      // We set its own virtual view ID to `kUnsetID` and return early.
+      MOZ_ASSERT(!registeredAcc || IsDetachedDoc(aAccessible),
+                 "Accessible is detached document");
+      AccessibleWrap::SetVirtualViewID(aAccessible, kUnsetID);
+      return;
+    }
+
+    MOZ_ASSERT(registeredAcc, "Unregistering unregistered accessible");
+    MOZ_ASSERT(registeredAcc == aAccessible, "Unregistering wrong accessible");
     sessionAcc->mIDToAccessibleMap.Remove(virtualViewID);
   }
 

accessible/basetypes/Accessible.cpp

@@ -396,7 +396,11 @@ void Accessible::DebugPrint(const char* aPrefix,
                             const Accessible* aAccessible) {
   nsAutoCString desc;
   aAccessible->DebugDescription(desc);
+#  if defined(ANDROID)
+  printf_stderr("%s %s\n", aPrefix, desc.get());
+#  else
   printf("%s %s\n", aPrefix, desc.get());
+#  endif
 }
 
 #endif

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/AccessibilityTest.kt

@@ -1348,6 +1348,25 @@ class AccessibilityTest : BaseSessionTest() {
         assertThat("Button has correct text", buttonNode.text.toString(), equalTo("Submit"))
     }
 
+    @Test fun testLoadUnloadIframeDoc() {
+        mainSession.loadTestPath(REMOTE_IFRAME)
+        waitForInitialFocus()
+
+        loadTestPage("test-tree")
+        waitForInitialFocus()
+
+        mainSession.loadTestPath(REMOTE_IFRAME)
+        waitForInitialFocus()
+
+        loadTestPage("test-tree")
+        waitForInitialFocus()
+
+        mainSession.loadTestPath(REMOTE_IFRAME)
+        waitForInitialFocus()
+
+        loadTestPage("test-tree")
+        waitForInitialFocus()
+    }
 
     private fun testAccessibilityFocusIframe(page: String) {
         var nodeId = AccessibilityNodeProvider.HOST_VIEW_ID