[Prerender] Get the prerender mode from Finch field trial.

chrome/browser/prerender/prerender_unittest.cc

 // Copyright (c) 2012 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 <stddef.h>
 #include <stdint.h>
 
 #include <map>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/format_macros.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/stringprintf.h"
+#include "base/test/scoped_feature_list.h"
 #include "base/test/simple_test_clock.h"
 #include "base/test/simple_test_tick_clock.h"
 #include "base/time/time.h"
 #include "chrome/browser/net/prediction_options.h"
 #include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
 #include "chrome/browser/prerender/prerender_handle.h"
 #include "chrome/browser/prerender/prerender_link_manager.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/prerender/prerender_origin.h"
@@ skipping 376 matching lines @@
   TestingProfile profile_;
   std::unique_ptr<UnitTestPrerenderManager> prerender_manager_;
   std::unique_ptr<PrerenderLinkManager> prerender_link_manager_;
   int last_prerender_id_;
   base::FieldTrialList field_trial_list_;
 };
 
 TEST_F(PrerenderTest, PrerenderRespectsDisableFlag) {
   RestorePrerenderMode restore_prerender_mode;
   ASSERT_TRUE(PrerenderManager::IsPrerenderingPossible());
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  command_line->AppendSwitchASCII(
-    switches::kPrerenderMode,
-    switches::kPrerenderModeSwitchValueDisabled);
-  prerender::ConfigurePrerender(*command_line);
-  ASSERT_FALSE(PrerenderManager::IsPrerenderingPossible());
+  {
+    base::test::ScopedFeatureList scoped_feature_list;
+    scoped_feature_list.InitAndDisableFeature(kNoStatePrefetchFeature);

[pasko, 2016/12/01 16:47:58]

please also test setting the "simple_load"

[droger, 2016/12/05 14:48:27]

Done.

+    prerender::ConfigurePrerender();
+    ASSERT_FALSE(PrerenderManager::IsPrerenderingPossible());
+  }
 }
 
 TEST_F(PrerenderTest, PrerenderRespectsThirdPartyCookiesPref) {
   GURL url("http://www.google.com/");
   RestorePrerenderMode restore_prerender_mode;
   ASSERT_TRUE(PrerenderManager::IsPrerenderingPossible());
 
   profile()->GetPrefs()->SetBoolean(prefs::kBlockThirdPartyCookies, true);
   EXPECT_FALSE(AddSimplePrerender(url));
 }
@@ skipping 1334 matching lines @@
   prerender_contents->SetPrerenderMode(PREFETCH_ONLY);
   EXPECT_TRUE(prerender_contents->IsValidHttpMethod("GET"));
   EXPECT_TRUE(prerender_contents->IsValidHttpMethod("HEAD"));
   EXPECT_FALSE(prerender_contents->IsValidHttpMethod("OPTIONS"));
   EXPECT_FALSE(prerender_contents->IsValidHttpMethod("POST"));
   EXPECT_FALSE(prerender_contents->IsValidHttpMethod("TRACE"));
   EXPECT_FALSE(prerender_contents->IsValidHttpMethod("WHATEVER"));
 }
 
 }  // namespace prerender