Fix AppModalDialogHelper to deal with a TabStrip without an active tab

chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc

Index: chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc
diff --git a/chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc b/chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc
index 05b0f921b337ce8ea50b76c848493686d8b99038..fb61052b8c692f54cdb1b177cf110d668f71d1fc 100644
--- a/chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc
+++ b/chrome/browser/ui/blocked_content/app_modal_dialog_helper.cc
@@ -16,18 +16,20 @@ AppModalDialogHelper::AppModalDialogHelper(content::WebContents* dialog_host)
   // If the WebContents that triggered this dialog is not currently focused, we
   // want to store a potential popup here to restore it after the dialog was
   // closed.
-  chrome::HostDesktopType desktop_type =
-      chrome::GetHostDesktopTypeForNativeView(dialog_host->GetNativeView());
-  Browser* active_browser =
-      BrowserList::GetInstance(desktop_type)->GetLastActive();
-  content::WebContents* active_web_contents =
-      active_browser->tab_strip_model()->GetActiveWebContents();
-  if (active_browser->is_type_popup() &&
-      active_web_contents->GetOpener() == dialog_host) {
-    // It's indeed a popup from the dialog opening WebContents. Store it, so
-    // we can focus it later.
-    popup_ = active_web_contents;
-    Observe(popup_);
+  if (dialog_host) {

[Bernhard Bauer, 2014/12/22 13:18:35]

Why do you even construct this object if you don't do anything for a null dialog
host?

+    chrome::HostDesktopType desktop_type =
+        chrome::GetHostDesktopTypeForNativeView(dialog_host->GetNativeView());
+    Browser* active_browser =
+        BrowserList::GetInstance(desktop_type)->GetLastActive();
+    content::WebContents* active_web_contents =
+        active_browser->tab_strip_model()->GetActiveWebContents();
+    if (active_browser->is_type_popup() &&
+        active_web_contents->GetOpener() == dialog_host) {
+      // It's indeed a popup from the dialog opening WebContents. Store it, so
+      // we can focus it later.
+      popup_ = active_web_contents;
+      Observe(popup_);
+    }
   }
 }