bug 1098386 - Allow PDocAccessibleConstructor to be recieved when gAccessibilityService doesn't exist r=surkov

Talos causes accessibility to be instantiated only in the content
process.  That means PDocAccessibleConstructor messages can be recieved
by the parent when GetAccService() returns null.  The easiest way of
dealing with this is moving DocManager::mRemoteDocuments from a member
of the acc service singleton to its own global.  That means the parent
process can track accessible documents in child processes without
instantiating a11y in the parent process.

accessible/base/DocManager.cpp

@@ -36,6 +36,8 @@ using namespace mozilla;
 using namespace mozilla::a11y;
 using namespace mozilla::dom;
 
+StaticAutoPtr<nsTArray<DocAccessibleParent*>> DocManager::sRemoteDocuments;
+
 ////////////////////////////////////////////////////////////////////////////////
 // DocManager
 ////////////////////////////////////////////////////////////////////////////////

accessible/base/DocManager.h

@@ -5,12 +5,14 @@
 #ifndef mozilla_a11_DocManager_h_
 #define mozilla_a11_DocManager_h_
 
+#include "mozilla/ClearOnShutdown.h"
 #include "nsIDocument.h"
 #include "nsIDOMEventListener.h"
 #include "nsRefPtrHashtable.h"
 #include "nsIWebProgressListener.h"
 #include "nsWeakReference.h"
 #include "nsIPresShell.h"
+#include "mozilla/StaticPtr.h"
 
 namespace mozilla {
 namespace a11y {
@@ -74,20 +76,24 @@ public:
   /*
    * Notification that a top level document in a content process has gone away.
    */
-  void RemoteDocShutdown(DocAccessibleParent* aDoc)
+  static void RemoteDocShutdown(DocAccessibleParent* aDoc)
   {
-    DebugOnly<bool> result = mRemoteDocuments.RemoveElement(aDoc);
+    DebugOnly<bool> result = sRemoteDocuments->RemoveElement(aDoc);
     MOZ_ASSERT(result, "Why didn't we find the document!");
   }
 
   /*
    * Notify of a new top level document in a content process.
    */
-  void RemoteDocAdded(DocAccessibleParent* aDoc)
+  static void RemoteDocAdded(DocAccessibleParent* aDoc)
   {
-    MOZ_ASSERT(!mRemoteDocuments.Contains(aDoc),
+    if (!sRemoteDocuments) {
+      sRemoteDocuments = new nsTArray<DocAccessibleParent*>;
+      ClearOnShutdown(&sRemoteDocuments);
+    }
+    MOZ_ASSERT(!sRemoteDocuments->Contains(aDoc),
                "How did we already have the doc!");
-    mRemoteDocuments.AppendElement(aDoc);
+    sRemoteDocuments->AppendElement(aDoc);
   }
 
 #ifdef DEBUG
@@ -176,7 +182,7 @@ private:
   /*
    * The list of remote top level documents.
    */
-  nsTArray<DocAccessibleParent*> mRemoteDocuments;
+  static StaticAutoPtr<nsTArray<DocAccessibleParent*>> sRemoteDocuments;
 };
 
 /**

dom/ipc/ContentParent.cpp

@@ -2868,7 +2868,7 @@ ContentParent::RecvPDocAccessibleConstructor(PDocAccessibleParent* aDoc, PDocAcc
     return parentDoc->AddChildDoc(doc, aParentID);
   } else {
     MOZ_ASSERT(!aParentID);
-    GetAccService()->RemoteDocAdded(doc);
+    a11y::DocManager::RemoteDocAdded(doc);
   }
 #endif
   return true;