Extensions-related fixups for scoped_refptr conversion operator removal.

BUG=110610
[email protected]

Review URL: https://codereview.chromium.org/510313002

Cr-Commit-Position: refs/heads/master@{#292420}
diff --git a/chrome/browser/extensions/test_extension_prefs.cc b/chrome/browser/extensions/test_extension_prefs.cc
index 30abaf4..51e5557 100644
--- a/chrome/browser/extensions/test_extension_prefs.cc
+++ b/chrome/browser/extensions/test_extension_prefs.cc
@@ -60,7 +60,8 @@
 
 }  // namespace
 
-TestExtensionPrefs::TestExtensionPrefs(base::SequencedTaskRunner* task_runner)
+TestExtensionPrefs::TestExtensionPrefs(
+    const scoped_refptr<base::SequencedTaskRunner>& task_runner)
     : task_runner_(task_runner), extensions_disabled_(false) {
   EXPECT_TRUE(temp_dir_.CreateUniqueTempDir());
   preferences_file_ = temp_dir_.path().Append(chrome::kPreferencesFilename);