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

chrome/browser/chrome_browser_field_trials.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 "chrome/browser/chrome_browser_field_trials.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/feature_list.h"
@@ skipping 108 matching lines @@
   if (has_seed)
     return;
 
   ChromeMetricsServicesManagerClient::CreateFallbackSamplingTrial(
       chrome::GetChannel(), feature_list);
 #endif  // defined(OS_WIN) || defined(OS_ANDROID)
 }
 
 }  // namespace
 
-ChromeBrowserFieldTrials::ChromeBrowserFieldTrials(
-    const base::CommandLine& parsed_command_line)
-    : parsed_command_line_(parsed_command_line) {
-}
+ChromeBrowserFieldTrials::ChromeBrowserFieldTrials() {}
 
 ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() {
 }
 
 void ChromeBrowserFieldTrials::SetupFieldTrials() {
   // Field trials that are shared by all platforms.
   InstantiateDynamicTrials();
 
 #if defined(OS_ANDROID)
-  chrome::SetupMobileFieldTrials(parsed_command_line_);
+  chrome::SetupMobileFieldTrials();
 #else
-  chrome::SetupDesktopFieldTrials(parsed_command_line_);
+  chrome::SetupDesktopFieldTrials();
 #endif
 }
 
 void ChromeBrowserFieldTrials::SetupFeatureControllingFieldTrials(
     bool has_seed,
     base::FeatureList* feature_list) {
   CreateFallbackSamplingTrialIfNeeded(has_seed, feature_list);
 }
 
 void ChromeBrowserFieldTrials::InstantiateDynamicTrials() {
   // Persistent histograms must be enabled as soon as possible.
   InstantiatePersistentHistograms();
   tracing::SetupBackgroundTracingFieldTrial();
 }