bug 1128751 - handle unbinding and rebinding of documents in content processes r=davidb

The code for managing document lifetimes assumed documents could not be
rebound to parents, however that is not the case.

accessible/base/NotificationController.cpp

@@ -280,12 +280,19 @@ NotificationController::WillRefresh(mozilla::TimeStamp aTime)
     size_t newDocCount = newChildDocs.Length();
     for (size_t i = 0; i < newDocCount; i++) {
       DocAccessible* childDoc = newChildDocs[i];
-      DocAccessibleChild* ipcDoc = new DocAccessibleChild(childDoc);
+      Accessible* parent = childDoc->Parent();
+      DocAccessibleChild* parentIPCDoc = mDocument->IPCDoc();
+      uint64_t id = reinterpret_cast<uintptr_t>(parent->UniqueID());
+      MOZ_ASSERT(id);
+      DocAccessibleChild* ipcDoc = childDoc->IPCDoc();
+      if (ipcDoc) {
+        parentIPCDoc->SendBindChildDoc(ipcDoc, id);
+        continue;
+      }
+
+      ipcDoc = new DocAccessibleChild(childDoc);
       childDoc->SetIPCDoc(ipcDoc);
       auto contentChild = dom::ContentChild::GetSingleton();
-      DocAccessibleChild* parentIPCDoc = mDocument->IPCDoc();
-      uint64_t id = reinterpret_cast<uintptr_t>(childDoc->Parent()->UniqueID());
-      MOZ_ASSERT(id);
       contentChild->SendPDocAccessibleConstructor(ipcDoc, parentIPCDoc, id);
     }
   }

accessible/base/nsAccessibilityService.h

@@ -279,8 +279,6 @@ GetAccService()
 inline bool
 IPCAccessibilityActive()
 {
-	// XXX reenable when crashes are fixed
-	return false;
 #ifdef MOZ_B2G
   return false;
 #else

accessible/ipc/DocAccessibleParent.cpp

@@ -137,9 +137,19 @@ DocAccessibleParent::RecvEvent(const uint64_t& aID, const uint32_t& aEventType)
   ProxyEvent(e->mProxy, aEventType);
   return true;
 }
+
+bool
+DocAccessibleParent::RecvBindChildDoc(PDocAccessibleParent* aChildDoc, const uint64_t& aID)
+{
+  auto childDoc = static_cast<DocAccessibleParent*>(aChildDoc);
+  DebugOnly<bool> result = AddChildDoc(childDoc, aID, false);
+  MOZ_ASSERT(result);
+  return true;
+}
+
 bool
 DocAccessibleParent::AddChildDoc(DocAccessibleParent* aChildDoc,
-                                 uint64_t aParentID)
+                                 uint64_t aParentID, bool aCreating)
 {
   ProxyAccessible* outerDoc = mAccessibles.GetEntry(aParentID)->mProxy;
   if (!outerDoc)
@@ -149,7 +159,11 @@ DocAccessibleParent::AddChildDoc(DocAccessibleParent* aChildDoc,
   outerDoc->SetChildDoc(aChildDoc);
   mChildDocs.AppendElement(aChildDoc);
   aChildDoc->mParentDoc = this;
-  ProxyCreated(aChildDoc, 0);
+
+  if (aCreating) {
+    ProxyCreated(aChildDoc, 0);
+  }
+
   return true;
 }
 

accessible/ipc/DocAccessibleParent.h

@@ -45,6 +45,14 @@ public:
   virtual bool RecvShowEvent(const ShowEventData& aData) override;
   virtual bool RecvHideEvent(const uint64_t& aRootID) override;
 
+  virtual bool RecvBindChildDoc(PDocAccessibleParent* aChildDoc, const uint64_t& aID) override;
+  void Unbind()
+  {
+    mParent = nullptr;
+    mParentDoc->mChildDocs.RemoveElement(this);
+    mParentDoc = nullptr;
+  }
+
   void Destroy();
   virtual void ActorDestroy(ActorDestroyReason aWhy) override
   {
@@ -62,7 +70,8 @@ public:
    * Called when a document in a content process notifies the main process of a
    * new child document.
    */
-  bool AddChildDoc(DocAccessibleParent* aChildDoc, uint64_t aParentID);
+  bool AddChildDoc(DocAccessibleParent* aChildDoc, uint64_t aParentID,
+                   bool aCreating = true);
 
   /*
    * Called when the document in the content process this object represents

accessible/ipc/PDocAccessible.ipdl

@@ -57,6 +57,12 @@ parent:
   ShowEvent(ShowEventData data);
   HideEvent(uint64_t aRootID);
 
+  /*
+   * Tell the parent document to bind the existing document as a new child
+   * document.
+   */
+  BindChildDoc(PDocAccessible aChildDoc, uint64_t aID);
+
 child:
   // Accessible
   prio(high) sync State(uint64_t aID) returns(uint64_t states);

accessible/ipc/ProxyAccessible.cpp

@@ -29,7 +29,7 @@ ProxyAccessible::Shutdown()
     if (mChildren.Length() != 1)
       MOZ_CRASH("outer doc doesn't own adoc!");
 
-    static_cast<DocAccessibleParent*>(mChildren[0])->Destroy();
+    static_cast<DocAccessibleParent*>(mChildren[0])->Unbind();
   }
 
   mChildren.Clear();