Add HttpProtocolHandler and convert everything to use it

components/cronet/ios/cronet_environment.cc

Index: components/cronet/ios/cronet_environment.cc
diff --git a/components/cronet/ios/cronet_environment.cc b/components/cronet/ios/cronet_environment.cc
index 00c1fd513373ce48095c3d97b7831bbd594603a1..2f4bcd7fc456c18d0960abdf73bdc2b0e99a04b4 100644
--- a/components/cronet/ios/cronet_environment.cc
+++ b/components/cronet/ios/cronet_environment.cc
@@ -352,9 +352,9 @@ void CronetEnvironment::InitializeOnNetworkThread() {
                          true /* set_up_quic_server_info */);
   main_context_->set_http_transaction_factory(main_cache);
 
-  net::URLRequestJobFactoryImpl* job_factory =
-      new net::URLRequestJobFactoryImpl;
-  main_context_->set_job_factory(job_factory);
+  std::unique_ptr<net::URLRequestJobFactoryImpl> job_factory =
+      net::URLRequestJobFactoryImpl::CreateWithDefaultProtocolHandlers();

[mmenke, 2016/04/22 18:37:52]

Could you add a TODO about fixing this leak?

[mgersh, 2016/04/22 20:27:15]

This function, and the crnet equivalent, already have two TODOs about this,
including one about five lines up from here, which link to a bug that applies to
the entire thing. Do you think it needs another one specifically here?

[mmenke, 2016/04/22 20:41:04]

I'd say yes, just to make it clearer that this is yet another instance of a
leak.  Or could update the comments about fixing leaks to make it clearer that
this is also being leaked.

[mgersh, 2016/04/27 16:13:52]

Done.

+  main_context_->set_job_factory(job_factory.release());
   main_context_->set_net_log(net_log_.get());
 }