Bug 1558390: For OOP iframes, also send the embedder accessible when the BrowserBridgeChild is created. r=yzen,nika

Previously, BrowserBridgeChild::SendSetEmbedderAccessible was only called when an OuterDocAccessible was constructed.
However, it's also possible that the BrowserBridgeChild is created *after* the OuterDocAccessible.
Therefore, we must also do this when a BrowserBridgeChild is created if the OuterDocAccessible already exists.

Differential Revision: https://phabricator.services.mozilla.com/D34474

--HG--
extra : moz-landing-system : lando

accessible/base/AccEvent.h

@@ -20,6 +20,7 @@ class Selection;
 namespace a11y {
 
 class DocAccessible;
+class EventQueue;
 
 // Constants used to point whether the event is from user input.
 enum EIsFromUserInput {

accessible/generic/OuterDocAccessible.cpp

@@ -37,14 +37,8 @@ OuterDocAccessible::OuterDocAccessible(nsIContent* aContent,
   if (IPCAccessibilityActive()) {
     auto bridge = dom::BrowserBridgeChild::GetFrom(aContent);
     if (bridge) {
-      // This is an iframe which will be rendered in another process. Tell the
-      // parent process the iframe accessible so it can link the
-      // trees together when the iframe document is added.
-      DocAccessibleChild* ipcDoc = aDoc->IPCDoc();
-      if (ipcDoc) {
-        uint64_t id = reinterpret_cast<uintptr_t>(UniqueID());
-        bridge->SendSetEmbedderAccessible(ipcDoc, id);
-      }
+      // This is an iframe which will be rendered in another process.
+      SendEmbedderAccessible(bridge);
     }
   }
 
@@ -59,6 +53,16 @@ OuterDocAccessible::OuterDocAccessible(nsIContent* aContent,
 
 OuterDocAccessible::~OuterDocAccessible() {}
 
+void OuterDocAccessible::SendEmbedderAccessible(
+    dom::BrowserBridgeChild* aBridge) {
+  MOZ_ASSERT(mDoc);
+  DocAccessibleChild* ipcDoc = mDoc->IPCDoc();
+  if (ipcDoc) {
+    uint64_t id = reinterpret_cast<uintptr_t>(UniqueID());
+    aBridge->SendSetEmbedderAccessible(ipcDoc, id);
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Accessible public (DON'T add methods here)
 

accessible/generic/OuterDocAccessible.h

@@ -9,6 +9,11 @@
 #include "AccessibleWrap.h"
 
 namespace mozilla {
+
+namespace dom {
+class BrowserBridgeChild;
+}
+
 namespace a11y {
 class DocAccessibleParent;
 
@@ -32,6 +37,16 @@ class OuterDocAccessible final : public AccessibleWrap {
   Accessible* RemoteChildDocAccessible() const;
 #endif
 
+  /**
+   * For iframes in a content process which will be rendered in another content
+   * process, tell the parent process about this OuterDocAccessible
+   * so it can link the trees together when the embedded document is added.
+   * Note that an OuterDocAccessible can be created before the
+   * BrowserBridgeChild or vice versa. Therefore, this must be conditionally
+   * called when either of these is created.
+   */
+  void SendEmbedderAccessible(dom::BrowserBridgeChild* aBridge);
+
   // Accessible
   virtual void Shutdown() override;
   virtual mozilla::a11y::role NativeRole() const override;

accessible/generic/moz.build

@@ -8,6 +8,7 @@ EXPORTS.mozilla.a11y += [
     'Accessible.h',
     'DocAccessible.h',
     'HyperTextAccessible.h',
+    'OuterDocAccessible.h',
 ]
 
 UNIFIED_SOURCES += [

dom/ipc/ContentChild.cpp

@@ -225,6 +225,9 @@
 #  ifdef XP_WIN
 #    include "mozilla/a11y/AccessibleWrap.h"
 #  endif
+#  include "mozilla/a11y/DocAccessible.h"
+#  include "mozilla/a11y/DocManager.h"
+#  include "mozilla/a11y/OuterDocAccessible.h"
 #endif
 
 #include "mozilla/dom/File.h"
@@ -2067,6 +2070,20 @@ already_AddRefed<RemoteBrowser> ContentChild::CreateBrowser(
       aBrowsingContext, chromeFlags, tabId);
   browserBridge->mIPCOpen = true;
 
+#if defined(ACCESSIBILITY)
+  a11y::DocAccessible* docAcc =
+      a11y::GetExistingDocAccessible(owner->OwnerDoc());
+  if (docAcc) {
+    a11y::Accessible* ownerAcc = docAcc->GetAccessible(owner);
+    if (ownerAcc) {
+      a11y::OuterDocAccessible* outerAcc = ownerAcc->AsOuterDoc();
+      if (outerAcc) {
+        outerAcc->SendEmbedderAccessible(browserBridge);
+      }
+    }
+  }
+#endif  // defined(ACCESSIBILITY)
+
   RefPtr<BrowserBridgeHost> browserBridgeHost =
       new BrowserBridgeHost(browserBridge);
   return browserBridgeHost.forget();