Convert OCSPRequestSessionDelegateURLRequest to OnceCallback.

Bug: 1007815
Change-Id: I406a6de24c91a09220cf9a4b5cbba53980b2400b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2091745
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748251}

net/cert_net/nss_ocsp_session_url_request.cc

@@ -116,8 +116,9 @@ class OCSPRequestSessionDelegateURLRequest : public OCSPRequestSessionDelegate,
   std::unique_ptr<OCSPRequestSessionResult> StartAndWait(
       const OCSPRequestSessionParams* params) override {
     GetOCSPIOLoop()->PostTaskToIOLoop(
-        FROM_HERE, base::Bind(&OCSPRequestSessionDelegateURLRequest::StartLoad,
-                              this, params));
+        FROM_HERE,
+        base::BindOnce(&OCSPRequestSessionDelegateURLRequest::StartLoad, this,
+                       params));
 
     // Wait with a timeout.
     base::TimeDelta timeout = params->timeout;