Bug 1631276 part 2: On non-Windows, have the parent process notify the content process when the DocAccessibleParent is constructed. r=eeejay

This is already handled in a different way on Windows.
For documents at the top level of their process (including OOP iframes), we can just set the flag rather than waiting for a message, since we can never get queries for such documents or descendants before parent process construction is complete.

Differential Revision: https://phabricator.services.mozilla.com/D81009

accessible/generic/DocAccessible.cpp

@@ -1641,6 +1641,13 @@ void DocAccessible::DoInitialUpdate() {
           ipcDoc->SendPDocAccessiblePlatformExtConstructor();
 #endif
         }
+#if !defined(XP_WIN)
+        // It's safe for us to mark top level documents as constructed in the
+        // parent process without receiving an explicit message, since we can
+        // never get queries for this document or descendants before parent
+        // process construction is complete.
+        ipcDoc->SetConstructedInParentProcess();
+#endif
       }
     }
   }

accessible/ipc/DocAccessibleChildBase.h

@@ -77,6 +77,8 @@ class DocAccessibleChildBase : public PDocAccessibleChild {
 
   DocAccessible* mDoc;
   bool mIsRemoteConstructed;
+
+  friend void DocAccessible::DoInitialUpdate();
 };
 
 }  // namespace a11y

accessible/ipc/other/DocAccessibleChild.cpp

@@ -1694,6 +1694,11 @@ mozilla::ipc::IPCResult DocAccessibleChild::RecvDOMNodeID(
   return IPC_OK();
 }
 
+mozilla::ipc::IPCResult DocAccessibleChild::RecvConstructedInParentProcess() {
+  SetConstructedInParentProcess();
+  return IPC_OK();
+}
+
 mozilla::ipc::IPCResult DocAccessibleChild::RecvRestoreFocus() {
   FocusMgr()->ForceFocusEvent();
   return IPC_OK();

accessible/ipc/other/DocAccessibleChild.h

@@ -38,6 +38,7 @@ class DocAccessibleChild : public DocAccessibleChildBase {
     MOZ_COUNT_DTOR_INHERITED(DocAccessibleChild, DocAccessibleChildBase);
   }
 
+  virtual mozilla::ipc::IPCResult RecvConstructedInParentProcess() override;
   virtual mozilla::ipc::IPCResult RecvRestoreFocus() override;
 
   /*

accessible/ipc/other/PDocAccessible.ipdl

@@ -124,6 +124,12 @@ parent:
   async Batch(uint64_t aBatchType, BatchData[] aData);
 
 child:
+  /*
+   * Notify the content process that the PDocAccessible has finished being
+   * constructed in the parent process.
+   */
+  async ConstructedInParentProcess();
+
   async __delete__();
 
   /*

dom/ipc/BrowserParent.cpp

@@ -1209,6 +1209,8 @@ mozilla::ipc::IPCResult BrowserParent::RecvPDocAccessibleConstructor(
     if (a11y::nsWinUtils::IsWindowEmulationStarted()) {
       doc->SetEmulatedWindowHandle(parentDoc->GetEmulatedWindowHandle());
     }
+#  else
+    Unused << aDoc->SendConstructedInParentProcess();
 #  endif
 
     return IPC_OK();