2 files changed, 20 insertions, 2 deletions

diff --git a/chrome/browser/app_modal_dialog_queue.cc b/chrome/browser/app_modal_dialog_queue.cc
index 3d4f2da..bcf1859 100644
--- a/chrome/browser/app_modal_dialog_queue.cc
+++ b/chrome/browser/app_modal_dialog_queue.cc
@@ -23,13 +23,27 @@ void AppModalDialogQueue::ShowNextDialog() {
 }
 
 void AppModalDialogQueue::ActivateModalDialog() {
+  if (showing_modal_dialog_) {
+    // As part of showing a modal dialog we may end up back in this method
+    // (showing a dialog activates the TabContents, which can trigger a call
+    // to ActivateModalDialog). We ignore such a request as after the call to
+    // activate the tab contents the dialog is shown.
+    return;
+  }
   if (active_dialog_)
     active_dialog_->ActivateModalDialog();
 }
 
 void AppModalDialogQueue::ShowModalDialog(AppModalDialog* dialog) {
-  dialog->ShowModalDialog();
+  // Be sure and set the active_dialog_ field first, otherwise if
+  // ShowModalDialog triggers a call back to the queue they'll get the old
+  // dialog. Also, if the dialog calls |ShowNextDialog()| before returning, that
+  // would write NULL into |active_dialog_| and this function would then undo
+  // that.
   active_dialog_ = dialog;
+  showing_modal_dialog_ = true;
+  dialog->ShowModalDialog();
+  showing_modal_dialog_ = false;
 }
 
 AppModalDialog* AppModalDialogQueue::GetNextDialog() {
diff --git a/chrome/browser/app_modal_dialog_queue.h b/chrome/browser/app_modal_dialog_queue.h
index 66ba3ff..b9709b3 100644
--- a/chrome/browser/app_modal_dialog_queue.h
+++ b/chrome/browser/app_modal_dialog_queue.h
@@ -54,7 +54,7 @@ class AppModalDialogQueue {
  private:
   friend struct DefaultSingletonTraits<AppModalDialogQueue>;
 
-  AppModalDialogQueue() : active_dialog_(NULL) {}
+  AppModalDialogQueue() : active_dialog_(NULL), showing_modal_dialog_(false) {}
 
   // Shows |dialog| and notifies the BrowserList that a modal dialog is showing.
   void ShowModalDialog(AppModalDialog* dialog);
@@ -73,6 +73,10 @@ class AppModalDialogQueue {
   // active app-modal dialog box.
   AppModalDialog* active_dialog_;
 
+  // Stores if |ShowModalDialog()| is currently being called on an app-modal
+  // dialog.
+  bool showing_modal_dialog_;
+
   DISALLOW_COPY_AND_ASSIGN(AppModalDialogQueue);
 };