Add an about:flag to enable client-side LoFi

components/previews/core/previews_experiments_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/previews/core/previews_experiments.h"
 
 #include <map>
 #include <string>
 
 #include "base/feature_list.h"
@@ skipping 148 matching lines @@
       base::FieldTrialList::CreateFieldTrial(kClientLoFiFieldTrial, kEnabled));
 
   EXPECT_TRUE(params::IsClientLoFiEnabled());
   EXPECT_EQ(10, params::ClientLoFiVersion());
   EXPECT_EQ(net::EFFECTIVE_CONNECTION_TYPE_3G,
             params::EffectiveConnectionTypeThresholdForClientLoFi());
 
   variations::testing::ClearAllVariationParams();
 }
 
+// Verifies that we can enable offline previews via comand line.
+TEST(PreviewsExperimentsTest, TestCommandLineClientLoFi) {
+  EXPECT_FALSE(params::IsClientLoFiEnabled());
+
+  std::unique_ptr<base::FeatureList> feature_list =
+      base::MakeUnique<base::FeatureList>();
+
+  // The feature is explicitly enabled on the command-line.
+  feature_list->InitializeFromCommandLine("ClientLoFi", "");
+  base::FeatureList::ClearInstanceForTesting();
+  base::FeatureList::SetInstance(std::move(feature_list));
+
+  EXPECT_TRUE(params::IsClientLoFiEnabled());
+  base::FeatureList::ClearInstanceForTesting();
+}
+
 }  // namespace
 
 }  // namespace previews