Adding macro to enable changing SSL library (Part 1)

ios/web/app/web_main_loop.mm

 // Copyright 2014 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 "ios/web/app/web_main_loop.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 36 matching lines @@
 
 void WebMainLoop::Init() {
   parts_.reset(web::GetWebClient()->CreateWebMainParts());
 }
 
 void WebMainLoop::EarlyInitialization() {
   if (parts_) {
     parts_->PreEarlyInitialization();
   }
 
+#if defined(USE_NSS_VERIFIER)
   // We want to be sure to init NSPR on the main thread.
   crypto::EnsureNSPRInit();
+#endif
 
   if (parts_) {
     parts_->PostEarlyInitialization();
   }
 }
 
 void WebMainLoop::MainMessageLoopStart() {
   if (parts_) {
     parts_->PreMainMessageLoopStart();
   }
@@ skipping 202 matching lines @@
   main_thread_.reset(
       new WebThreadImpl(WebThread::UI, base::MessageLoop::current()));
 }
 
 int WebMainLoop::WebThreadsStarted() {
   cookie_notification_bridge_.reset(new CookieNotificationBridge);
   return result_code_;
 }
 
 }  // namespace web