Remove command line/field trial support and configs for Isolate Extensions.

chrome/browser/browser_process_impl.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/browser_process_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <map>
@@ skipping 1060 matching lines @@
   int max_per_proxy = local_state_->GetInteger(prefs::kMaxConnectionsPerProxy);
   net::ClientSocketPoolManager::set_max_sockets_per_proxy_server(
       net::HttpNetworkSession::NORMAL_SOCKET_POOL,
       std::max(std::min(max_per_proxy, 99),
                net::ClientSocketPoolManager::max_sockets_per_group(
                    net::HttpNetworkSession::NORMAL_SOCKET_POOL)));
 }
 
 void BrowserProcessImpl::PreCreateThreads() {
 #if BUILDFLAG(ENABLE_EXTENSIONS)
-  // Register the chrome-extension scheme to reflect the extension process
-  // model. Controlled by a field trial, so we can't do this earlier.
-  base::FieldTrialList::FindFullName("SiteIsolationExtensions");
-  if (extensions::IsIsolateExtensionsEnabled()) {
-    // chrome-extension:// URLs are safe to request anywhere, but may only
-    // commit (including in iframes) in extension processes.
-    ChildProcessSecurityPolicy::GetInstance()->RegisterWebSafeIsolatedScheme(
-        extensions::kExtensionScheme, true);
-  } else {
-    ChildProcessSecurityPolicy::GetInstance()->RegisterWebSafeScheme(
-        extensions::kExtensionScheme);
-  }
+  // chrome-extension:// URLs are safe to request anywhere, but may only
+  // commit (including in iframes) in extension processes.
+  ChildProcessSecurityPolicy::GetInstance()->RegisterWebSafeIsolatedScheme(
+      extensions::kExtensionScheme, true);
 #endif
 
   io_thread_.reset(
       new IOThread(local_state(), policy_service(), net_log_.get(),
                    extension_event_router_forwarder()));
 }
 
 void BrowserProcessImpl::PreMainMessageLoopRun() {
   TRACE_EVENT0("startup", "BrowserProcessImpl::PreMainMessageLoopRun");
   SCOPED_UMA_HISTOGRAM_TIMER(
@@ skipping 332 matching lines @@
 }
 
 void BrowserProcessImpl::OnAutoupdateTimer() {
   if (CanAutorestartForUpdate()) {
     DLOG(WARNING) << "Detected update.  Restarting browser.";
     RestartBackgroundInstance();
   }
 }
 
 #endif  // (defined(OS_WIN) || defined(OS_LINUX)) && !defined(OS_CHROMEOS)