Removing NSS files and USE_OPENSSL flag

ios/chrome/browser/ios_chrome_io_thread.mm

Index: ios/chrome/browser/ios_chrome_io_thread.mm
diff --git a/ios/chrome/browser/ios_chrome_io_thread.mm b/ios/chrome/browser/ios_chrome_io_thread.mm
index 862fc4245b98881634548d8e838317d55d17ed83..f2d4f1b9c44de43e41cc2ec212aecf71af7dbc69 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.mm
+++ b/ios/chrome/browser/ios_chrome_io_thread.mm
@@ -147,17 +147,11 @@ const char kSpdyDepencenciesFieldTrialDisable[] = "Disable";
 class SystemURLRequestContext : public net::URLRequestContext {
  public:
   SystemURLRequestContext() {
-#if defined(USE_NSS_VERIFIER)
-    net::SetURLRequestContextForNSSHttpIO(this);
-#endif
   }
 
  private:
   ~SystemURLRequestContext() override {
     AssertNoURLRequests();
-#if defined(USE_NSS_VERIFIER)
-    net::SetURLRequestContextForNSSHttpIO(nullptr);
-#endif
   }
 };
 
@@ -390,10 +384,6 @@ void IOSChromeIOThread::Init() {
   TRACE_EVENT0("startup", "IOSChromeIOThread::Init");
   DCHECK_CURRENTLY_ON(web::WebThread::IO);
 
-#if defined(USE_NSS_VERIFIER)
-  net::SetMessageLoopForNSSHttpIO();
-#endif
-
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
 
@@ -492,10 +482,6 @@ void IOSChromeIOThread::Init() {
 }
 
 void IOSChromeIOThread::CleanUp() {
-#if defined(USE_NSS_VERIFIER)
-  net::ShutdownNSSHttpIO();
-#endif
-
   system_url_request_context_getter_ = nullptr;
 
   // Release objects that the net::URLRequestContext could have been pointing