Adding macro to enable changing SSL library (Part 1)

ios/chrome/browser/ios_chrome_io_thread.mm

 // Copyright 2015 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/chrome/browser/ios_chrome_io_thread.h"
 
 #include <stddef.h>
 
 #include <utility>
 #include <vector>
@@ skipping 122 matching lines @@
 const char kNetworkQualityEstimatorFieldTrialName[] = "NetworkQualityEstimator";
 
 // Field trial for NPN.
 const char kNpnTrialName[] = "NPN";
 const char kNpnTrialEnabledGroupNamePrefix[] = "Enable";
 const char kNpnTrialDisabledGroupNamePrefix[] = "Disable";
 
 // Used for the "system" URLRequestContext.
 class SystemURLRequestContext : public net::URLRequestContext {
  public:
-  SystemURLRequestContext() { net::SetURLRequestContextForNSSHttpIO(this); }
+  SystemURLRequestContext() {
+#if defined(USE_NSS_VERIFIER)
+    net::SetURLRequestContextForNSSHttpIO(this);
+#endif
+  }
 
  private:
   ~SystemURLRequestContext() override {
     AssertNoURLRequests();
+#if defined(USE_NSS_VERIFIER)
     net::SetURLRequestContextForNSSHttpIO(nullptr);
+#endif
   }
 };
 
 scoped_ptr<net::HostResolver> CreateGlobalHostResolver(net::NetLog* net_log) {
   TRACE_EVENT0("startup", "IOSChromeIOThread::CreateGlobalHostResolver");
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
 
   scoped_ptr<net::HostResolver> global_host_resolver =
       net::HostResolver::CreateSystemResolver(net::HostResolver::Options(),
@@ skipping 211 matching lines @@
   if (!system_url_request_context_getter_.get()) {
     InitSystemRequestContext();
   }
   return system_url_request_context_getter_.get();
 }
 
 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();
 
   DCHECK(!globals_);
   globals_ = new Globals;
 
   // Add an observer that will emit network change events to the ChromeNetLog.
   // Assuming NetworkChangeNotifier dispatches in FIFO order, we should be
   // logging the network change before other IO thread consumers respond to it.
@@ skipping 76 matching lines @@
   // get it onto the message loop while the IOSChromeIOThread object still
   // exists.  However, the message might not be processed on the UI
   // thread until after IOSChromeIOThread is gone, so use a weak pointer.
   web::WebThread::PostTask(
       web::WebThread::UI, FROM_HERE,
       base::Bind(&IOSChromeIOThread::InitSystemRequestContext,
                  weak_factory_.GetWeakPtr()));
 }
 
 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
   // to.
 
   // Shutdown the HistogramWatcher on the IO thread.
   net::NetworkChangeNotifier::ShutdownHistogramWatcher();
 
   // This must be reset before the ChromeNetLog is destroyed.
@@ skipping 556 matching lines @@
 
   globals->system_http_network_session.reset(
       new net::HttpNetworkSession(system_params));
   globals->system_http_transaction_factory.reset(
       new net::HttpNetworkLayer(globals->system_http_network_session.get()));
   context->set_http_transaction_factory(
       globals->system_http_transaction_factory.get());
 
   return context;
 }