Tweaks to app modal dialog shutdown.

Make sure that an invalidated dialog doesn't call
AppModalDialogQueue::ShowNextDialog() during shutdown. This could
potentially cause issues as it causes ShowNextDialog to be reentrant,
which doesn't seem intentional.

Also remove an unnecessary check: the active dialog is not in the dialog
queue so we don't need to check the queue against the active dialog when
hiding a batch of dialogs.

Bug: 1060986
Change-Id: I962a5cf14c3f5b67d287de61464b604dbe96aaf7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2295822
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789242}

components/javascript_dialogs/app_modal_dialog_controller.cc

@@ -78,7 +78,6 @@ AppModalDialogController::AppModalDialogController(
     bool is_reload,
     content::JavaScriptDialogManager::DialogClosedCallback callback)
     : title_(title),
-      completed_(false),
       valid_(true),
       view_(nullptr),
       web_contents_(web_contents),
@@ -114,9 +113,13 @@ void AppModalDialogController::CloseModalDialog() {
 }
 
 void AppModalDialogController::CompleteDialog() {
-  if (!completed_) {
-    completed_ = true;
+  // If |view_| is non-null, then |this| is the active dialog and the next one
+  // should be shown. Otherwise, |this| was never shown.
+  if (view_) {
+    view_ = nullptr;
     AppModalDialogQueue::GetInstance()->ShowNextDialog();
+  } else {
+    DCHECK(!valid_);
   }
 }
 

components/javascript_dialogs/app_modal_dialog_controller.h

@@ -107,14 +107,12 @@ class AppModalDialogController {
   // The title of the dialog.
   const base::string16 title_;
 
-  // // True if CompleteDialog was called.
-  bool completed_;
-
   // False if the dialog should no longer be shown, e.g. because the underlying
   // tab navigated away while the dialog was queued.
   bool valid_;
 
-  // // The toolkit-specific implementation of the app modal dialog box.
+  // The toolkit-specific implementation of the app modal dialog box. When
+  // non-null, |view_| owns |this|.
   AppModalDialogView* view_;
 
   // The WebContents that opened this dialog.

components/javascript_dialogs/app_modal_dialog_manager.cc

@@ -278,15 +278,11 @@ bool AppModalDialogManager::HandleJavaScriptDialog(
 void AppModalDialogManager::CancelDialogs(content::WebContents* web_contents,
                                           bool reset_state) {
   AppModalDialogQueue* queue = AppModalDialogQueue::GetInstance();
-  AppModalDialogController* active_dialog = queue->active_dialog();
   for (auto* dialog : *queue) {
-    // Invalidating the active dialog might trigger showing a not-yet
-    // invalidated dialog, so invalidate the active dialog last.
-    if (dialog == active_dialog)
-      continue;
     if (dialog->web_contents() == web_contents)
       dialog->Invalidate();
   }
+  AppModalDialogController* active_dialog = queue->active_dialog();
   if (active_dialog && active_dialog->web_contents() == web_contents)
     active_dialog->Invalidate();