Bug 357583. Allow XPCOM clients to init accessibility when they use nsIAccessible. r=surkov, sr=roc

accessible/src/base/nsAccessNode.cpp

@@ -65,6 +65,7 @@
 #include "nsITimer.h"
 #include "nsRootAccessible.h"
 #include "nsIFocusController.h"
+#include "nsIObserverService.h"
 
 /* For documentation of the accessibility architecture, 
  * see http://lxr.mozilla.org/seamonkey/source/accessible/accessible-docs.html
@@ -224,6 +225,20 @@ void nsAccessNode::InitXPAccessibility()
   }
 
   gIsAccessibilityActive = PR_TRUE;
+  NotifyA11yInitOrShutdown();
+}
+
+void nsAccessNode::NotifyA11yInitOrShutdown()
+{
+  nsCOMPtr<nsIObserverService> obsService =
+    do_GetService("@mozilla.org/observer-service;1");
+  NS_ASSERTION(obsService, "No observer service to notify of a11y init/shutdown");
+  if (obsService) {
+    static const PRUnichar kInitIndicator[] = { '1', 0 };
+    static const PRUnichar kShutdownIndicator[] = { '0', 0 }; 
+    obsService->NotifyObservers(nsnull, "a11y-init-or-shutdown",
+                                gIsAccessibilityActive ? kInitIndicator  : kShutdownIndicator);
+  }
 }
 
 void nsAccessNode::ShutdownXPAccessibility()
@@ -244,6 +259,7 @@ void nsAccessNode::ShutdownXPAccessibility()
   ClearCache(gGlobalDocAccessibleCache);
 
   gIsAccessibilityActive = PR_FALSE;
+  NotifyA11yInitOrShutdown();
 }
 
 already_AddRefed<nsIPresShell> nsAccessNode::GetPresShell()

accessible/src/base/nsAccessNode.h

@@ -165,6 +165,11 @@ protected:
     PRBool mIsInitialized;
 #endif
 
+    /**
+     * Notify global nsIObserver's that a11y is getting init'd or shutdown
+     */
+    static void NotifyA11yInitOrShutdown();
+
     // Static data, we do our own refcounting for our static data
     static nsIStringBundle *gStringBundle;
     static nsIStringBundle *gKeyStringBundle;

layout/base/nsIPresShell.h

@@ -636,7 +636,8 @@ public:
   virtual void VerifyStyleTree() = 0;
 #endif
 
-  PRBool IsAccessibilityActive() { return mIsAccessibilityActive; }
+  static PRBool gIsAccessibilityActive;
+  static PRBool IsAccessibilityActive() { return gIsAccessibilityActive; }
 
   /**
    * Stop all active elements (plugins and the caret) in this presentation and

layout/base/nsPresShell.cpp

@@ -204,6 +204,8 @@
 static NS_DEFINE_CID(kCSSStyleSheetCID, NS_CSS_STYLESHEET_CID);
 static NS_DEFINE_IID(kRangeCID,     NS_RANGE_CID);
 
+PRBool nsIPresShell::gIsAccessibilityActive = PR_FALSE;
+
 // convert a color value to a string, in the CSS format #RRGGBB
 // *  - initially created for bugs 31816, 20760, 22963
 static void ColorToString(nscolor aColor, nsAutoString &aString);
@@ -1419,7 +1421,6 @@ NS_NewPresShell(nsIPresShell** aInstancePtrResult)
 
 PresShell::PresShell()
 {
-  mIsAccessibilityActive = PR_FALSE;
   mSelection = nsnull;
 #ifdef MOZ_REFLOW_PERF
   mReflowCountMgr = new ReflowCountMgr();
@@ -1577,6 +1578,9 @@ PresShell::Init(nsIDocument* aDocument,
       os->AddObserver(this, "user-sheet-removed", PR_FALSE);
 #ifdef MOZ_XUL
       os->AddObserver(this, "chrome-flush-skin-caches", PR_FALSE);
+#endif
+#ifdef ACCESSIBILITY
+      os->AddObserver(this, "a11y-init-or-shutdown", PR_FALSE);
 #endif
     }
   }
@@ -3343,7 +3347,7 @@ PresShell::CancelAllPendingReflows()
 #ifdef ACCESSIBILITY
 void nsIPresShell::InvalidateAccessibleSubtree(nsIContent *aContent)
 {
-  if (mIsAccessibilityActive) {
+  if (gIsAccessibilityActive) {
     nsCOMPtr<nsIAccessibilityService> accService = 
       do_GetService("@mozilla.org/accessibilityService;1");
     if (accService) {
@@ -5678,7 +5682,6 @@ PresShell::HandleEventInternal(nsEvent* aEvent, nsIView *aView,
       // We'll make sure the right number of Addref's occur before
       // handing this back to the accessibility client
       NS_STATIC_CAST(nsAccessibleEvent*, aEvent)->accessible = acc;
-      mIsAccessibilityActive = PR_TRUE;
       return NS_OK;
     }
   }
@@ -6397,6 +6400,11 @@ PresShell::Observe(nsISupports* aSubject,
     return NS_OK;
   }
 
+#ifdef ACCESSIBILITY
+  if (!nsCRT::strcmp(aTopic, "a11y-init-or-shutdown")) {
+    gIsAccessibilityActive = aData && *aData == '1';
+  }
+#endif
   NS_WARNING("unrecognized topic in PresShell::Observe");
   return NS_ERROR_FAILURE;
 }