Update PpdProvider threading model.

chromeos/printing/ppd_provider_unittest.cc

Index: chromeos/printing/ppd_provider_unittest.cc
diff --git a/chromeos/printing/ppd_provider_unittest.cc b/chromeos/printing/ppd_provider_unittest.cc
index 7061f156332241218219f108b4ddb3197f78e228..15d9e814ef1279f9abff74e4921e8474d4eadc2a 100644
--- a/chromeos/printing/ppd_provider_unittest.cc
+++ b/chromeos/printing/ppd_provider_unittest.cc
@@ -74,7 +74,7 @@ class PpdProviderTest : public ::testing::Test {
     auto provider_options = PpdProvider::Options();
     provider_options.quirks_server = kTestQuirksServer;
     ppd_provider_ = PpdProvider::Create(
-        kTestAPIKey, request_context_getter_,
+        kTestAPIKey, request_context_getter_.get(), loop_.task_runner().get(),
         PpdCache::Create(ppd_cache_temp_dir_.GetPath()), provider_options);
   }