Reland r59972: Eagerly set the IO loop used for OCSP.

net/ocsp/nss_ocsp.h

Index: net/ocsp/nss_ocsp.h
diff --git a/net/ocsp/nss_ocsp.h b/net/ocsp/nss_ocsp.h
index a31d025c493de0fc538476273ab92f88bd7fbbfa..97d69b95e834597c187ab8ad422d4edd1c8850a7 100644
--- a/net/ocsp/nss_ocsp.h
+++ b/net/ocsp/nss_ocsp.h
@@ -10,6 +10,11 @@ class URLRequestContext;
 
 namespace net {
 
+// Sets the MessageLoop for OCSP to the current message loop.
+// This should be called before EnsureOCSPInit() if you want to
+// control the message loop for OCSP.
+void SetMessageLoopForOCSP();
+
 // Initializes OCSP handlers for NSS.  This must be called before any
 // certificate verification functions.  This function is thread-safe, and OCSP
 // handlers will only ever be initialized once.