Re-add an early exit to GetOrCreateExtensionList. The safeguard is us…

…eful during testing but I had optimistically removed it because browser_tests were passing locally. However, the bots didn't like it.

TBR=kalman
BUG=328441

Review URL: https://codereview.chromium.org/136793006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244674 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/extension_message_bubble_controller.cc

@@ -130,6 +130,9 @@ void ExtensionMessageBubbleController::AcknowledgeExtensions() {
 }
 
 ExtensionIdList* ExtensionMessageBubbleController::GetOrCreateExtensionList() {
+  if (!service_)
+    return &extension_list_;  // Can occur during testing.
+
   if (!initialized_) {
     scoped_ptr<const ExtensionSet> extension_set(
         service_->GenerateInstalledExtensionsSet());