[cros] Prevent extensions from opening dialogs on Login screen.

chrome/browser/extensions/extension_host.cc

Index: chrome/browser/extensions/extension_host.cc
diff --git a/chrome/browser/extensions/extension_host.cc b/chrome/browser/extensions/extension_host.cc
index 5266a3312494a91bffabd0d5a8adb146c84858ba..c1bd02b08a191a1aac8fc33b2b20c2d909d2ed61 100644
--- a/chrome/browser/extensions/extension_host.cc
+++ b/chrome/browser/extensions/extension_host.cc
@@ -56,6 +56,10 @@
 #include "ui/base/layout.h"
 #include "ui/base/resource/resource_bundle.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/user_manager.h"
+#endif
+
 using WebKit::WebDragOperation;
 using WebKit::WebDragOperationsMask;
 using content::NativeWebKeyboardEvent;
@@ -411,6 +415,14 @@ void ExtensionHost::CloseContents(WebContents* contents) {
   }
 }
 
+#if defined(OS_CHROMEOS)
+bool ExtensionHost::ShouldSuppressDialogs() {
+  // Prevent extensions from creating dialogs while user session hasn't
+  // started yet.
+  return !chromeos::UserManager::Get()->IsSessionStarted();
+}
+#endif
+
 void ExtensionHost::OnStartDownload(
     content::WebContents* source, content::DownloadItem* download) {
   // If |source| is in the context of a Browser, show the DownloadShelf on that