[cronet] Add mechanism for restarting CronetEnvironment

components/cronet/ios/Cronet.mm

Index: components/cronet/ios/Cronet.mm
diff --git a/components/cronet/ios/Cronet.mm b/components/cronet/ios/Cronet.mm
index b883049b52d3fefab00ba5ac7b4ec128cc676e90..fb313b6314f06a97b50ab4d3e918c77cc87dc950 100644
--- a/components/cronet/ios/Cronet.mm
+++ b/components/cronet/ios/Cronet.mm
@@ -148,8 +148,9 @@ class CronetHttpProtocolHandlerDelegate
   gAcceptLanguages = acceptLanguages;
 }
 
+// TODO(lilyhoughton) this should either be removed, or made more sophisticated
 + (void)checkNotStarted {
-  CHECK(gChromeNet == NULL) << "Cronet is already started.";
+  // CHECK(gChromeNet == NULL) << "Cronet is already started.";
 }
 
 + (void)setHttp2Enabled:(BOOL)http2Enabled {
@@ -203,11 +204,16 @@ class CronetHttpProtocolHandlerDelegate
     gRequestFilterBlock = block;
 }
 
-+ (void)startInternal {
++ (void)initializeCronet {
   cronet::CronetEnvironment::Initialize();
+}
+
++ (void)startInternal {
   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]));
 
@@ -236,12 +242,14 @@ class CronetHttpProtocolHandlerDelegate
   dispatch_once(&onceToken, ^{
     if (![NSThread isMainThread]) {
       dispatch_sync(dispatch_get_main_queue(), ^(void) {
-        [self startInternal];
+        [self initializeCronet];

[mef, 2017/04/25 17:55:10]

maybe call cronet::CronetEnvironment::Initialize(); here and below and get rid
of initializeCronet?

[lilyhoughton, 2017/04/26 18:31:53]

Good call.  Done.

       });
     } else {
-      [self startInternal];
+      [self initializeCronet];
     }
   });
+
+  [self startInternal];

[mef, 2017/04/25 17:55:10]

This now will happen current thread instead of main thread, but I think that's
ok.

[lilyhoughton, 2017/04/26 18:31:53]

Acknowledged.

 }
 
 + (void)registerHttpProtocolHandler {