Bug 709492 - Part 1: Add an observer that allows us to determine when a new page is shown. r=bz

layout/base/nsDocumentViewer.cpp

@@ -194,6 +194,8 @@ static const char sPrintOptionsContractID[]         = "@mozilla.org/gfx/printset
 //switch to page layout
 #include "nsGfxCIID.h"
 
+#include "nsObserverService.h"
+
 #include "mozilla/dom/Element.h"
 
 using namespace mozilla;
@@ -509,6 +511,18 @@ public:
   nsCOMPtr<nsIDocument> mTop;
 };
 
+class nsDocumentShownDispatcher : public nsRunnable
+{
+public:
+  nsDocumentShownDispatcher(nsIDocument *aDocument)
+  : mDocument(aDocument) {}
+
+  NS_IMETHOD Run();
+
+private:
+  nsCOMPtr<nsIDocument> mDocument;
+};
+
 
 //------------------------------------------------------------------
 // DocumentViewerImpl
@@ -2039,6 +2053,10 @@ DocumentViewerImpl::Show(void)
     }
   }
 
+  // Notify observers that a new page has been shown. (But not right now;
+  // running JS at this time is not safe.)
+  NS_DispatchToMainThread(new nsDocumentShownDispatcher(mDocument));
+
   return NS_OK;
 }
 
@@ -4371,3 +4389,17 @@ DocumentViewerImpl::SetPrintPreviewPresentation(nsIViewManager* aViewManager,
   mPresContext = aPresContext;
   mPresShell = aPresShell;
 }
+
+// Fires the "document-shown" event so that interested parties (right now, the
+// mobile browser) are aware of it.
+NS_IMETHODIMP
+nsDocumentShownDispatcher::Run()
+{
+  nsCOMPtr<nsIObserverService> observerService =
+    mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->NotifyObservers(mDocument, "document-shown", NULL);
+  }
+  return NS_OK;
+}
+