Add a feature flag for network service and about:flags entry for it.

chrome/browser/chrome_content_browser_client.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_content_browser_client.h"
 
 #include <map>
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 2897 matching lines @@
       ui_task_runner);
   if (NetBenchmarking::CheckBenchmarkingEnabled()) {
     Profile* profile =
         Profile::FromBrowserContext(render_process_host->GetBrowserContext());
     net::URLRequestContextGetter* context =
         render_process_host->GetStoragePartition()->GetURLRequestContext();
     registry->AddInterface(base::Bind(&NetBenchmarking::Create, profile,
                                       base::RetainedRef(context)));
   }
 
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableNetworkService)) {
+  if (base::FeatureList::IsEnabled(features::kNetworkService)) {
     registry->AddInterface(
         base::Bind(&safe_browsing::MojoSafeBrowsingImpl::Create,
                    safe_browsing_service_->database_manager(),
                    safe_browsing_service_->ui_manager(),
                    render_process_host->GetID()),
         BrowserThread::GetTaskRunnerForThread(BrowserThread::IO));
   }
 
 #if defined(OS_WIN)
   if (base::FeatureList::IsEnabled(features::kModuleDatabase)) {
@@ skipping 473 matching lines @@
 }
 
 base::FilePath ChromeContentBrowserClient::GetLoggingFileName() {
   return logging::GetLogFileName();
 }
 
 std::vector<std::unique_ptr<content::URLLoaderThrottle>>
 ChromeContentBrowserClient::CreateURLLoaderThrottles(
     const base::Callback<content::WebContents*()>& wc_getter) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  DCHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableNetworkService));
+  DCHECK(base::FeatureList::IsEnabled(features::kNetworkService));
 
   std::vector<std::unique_ptr<content::URLLoaderThrottle>> result;
   result.push_back(base::MakeUnique<safe_browsing::BrowserURLLoaderThrottle>(
       safe_browsing_service_->database_manager(),
       safe_browsing_service_->ui_manager(), wc_getter));
   return result;
 }
 
 // Static; handles rewriting Web UI URLs.
 bool ChromeContentBrowserClient::HandleWebUI(
@@ skipping 40 matching lines @@
   // displayed URL when rewriting chrome://help to chrome://settings/help.
   return url->SchemeIs(content::kChromeUIScheme) &&
          url->host() == chrome::kChromeUISettingsHost;
 }
 
 // static
 void ChromeContentBrowserClient::SetDefaultQuotaSettingsForTesting(
     const storage::QuotaSettings* settings) {
   g_default_quota_settings = settings;
 }