[cronet] Add mechanism for restarting CronetEnvironment

components/cronet/ios/Cronet.mm

 // Copyright 2016 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.
 
 #import "components/cronet/ios/Cronet.h"
 
 #include <memory>
 
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 130 matching lines @@
 + (NSString*)getAcceptLanguages {
   return [self
       getAcceptLanguagesFromPreferredLanguages:[NSLocale preferredLanguages]];
 }
 
 + (void)setAcceptLanguages:(NSString*)acceptLanguages {
   [self checkNotStarted];
   gAcceptLanguages = acceptLanguages;
 }
 
+// TODO(lilyhoughton) this should either be removed, or made more sophisticated
 + (void)checkNotStarted {
-  CHECK(gChromeNet == NULL) << "Cronet is already started.";
+  CHECK(!gChromeNet.Get()) << "Cronet is already started.";
 }
 
 + (void)setHttp2Enabled:(BOOL)http2Enabled {
   [self checkNotStarted];
   gHttp2Enabled = http2Enabled;
 }
 
 + (void)setQuicEnabled:(BOOL)quicEnabled {
   [self checkNotStarted];
   gQuicEnabled = quicEnabled;
@@ skipping 34 matching lines @@
 }
 
 + (void)setRequestFilterBlock:(RequestFilterBlock)block {
   if (gHttpProtocolHandlerDelegate.Get().get())
     gHttpProtocolHandlerDelegate.Get().get()->SetRequestFilterBlock(block);
   else
     gRequestFilterBlock = block;
 }
 
 + (void)startInternal {
-  cronet::CronetEnvironment::Initialize();
   std::string user_agent = base::SysNSStringToUTF8(gUserAgent);
+
   gChromeNet.Get().reset(
       new cronet::CronetEnvironment(user_agent, gUserAgentPartial));
+
   gChromeNet.Get()->set_accept_language(
       base::SysNSStringToUTF8(gAcceptLanguages ?: [self getAcceptLanguages]));
 
   gChromeNet.Get()->set_http2_enabled(gHttp2Enabled);
   gChromeNet.Get()->set_quic_enabled(gQuicEnabled);
   gChromeNet.Get()->set_http_cache(gHttpCache);
   gChromeNet.Get()->set_ssl_key_log_file_name(
       base::SysNSStringToUTF8(gSslKeyLogFileName));
   for (const auto* quicHint : gQuicHints) {
     gChromeNet.Get()->AddQuicHint(quicHint->host, quicHint->port,
                                   quicHint->alternate_port);
   }
 
   [self configureCronetEnvironmentForTesting:gChromeNet.Get().get()];
   gChromeNet.Get()->Start();
   gHttpProtocolHandlerDelegate.Get().reset(
       new CronetHttpProtocolHandlerDelegate(
           gChromeNet.Get()->GetURLRequestContextGetter(), gRequestFilterBlock));
   net::HTTPProtocolHandlerDelegate::SetInstance(
       gHttpProtocolHandlerDelegate.Get().get());
   gRequestFilterBlock = nil;
 }
 
 + (void)start {
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
     if (![NSThread isMainThread]) {
       dispatch_sync(dispatch_get_main_queue(), ^(void) {
-        [self startInternal];
+        cronet::CronetEnvironment::Initialize();
       });
     } else {
-      [self startInternal];
+      cronet::CronetEnvironment::Initialize();
     }
   });
+
+  [self startInternal];
+}
+
++ (void)shutdownForTesting {
+  gChromeNet.Get().reset();
 }
 
 + (void)registerHttpProtocolHandler {
   if (gPreservedSharedURLCache == nil) {
     gPreservedSharedURLCache = [NSURLCache sharedURLCache];
   }
   // Disable the default cache.
   [NSURLCache setSharedURLCache:[EmptyNSURLCache emptyNSURLCache]];
   // Register the chrome http protocol handler to replace the default one.
   BOOL success =
@@ skipping 74 matching lines @@
       base::SysNSStringToUTF8(hostResolverRulesForTesting));
 }
 
 // This is a non-public dummy method that prevents the linker from stripping out
 // the otherwise non-referenced methods from 'bidirectional_stream.cc'.
 + (void)preventStrippingCronetBidirectionalStream {
   bidirectional_stream_create(NULL, 0, 0);
 }
 
 @end