Add UMA for SignedExchange verification time

Bug: 890180
Change-Id: I3cedfd4b03b534eabeb9573c226123bd3d70068e
Reviewed-on: https://chromium-review.googlesource.com/1250686Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595766}

content/browser/web_package/signed_exchange_signature_verifier.cc

@@ -233,6 +233,7 @@ SignedExchangeSignatureVerifier::Result SignedExchangeSignatureVerifier::Verify(
     scoped_refptr<net::X509Certificate> certificate,
     const base::Time& verification_time,
     SignedExchangeDevToolsProxy* devtools_proxy) {
+  SCOPED_UMA_HISTOGRAM_TIMER("SignedExchange.Time.SignatureVerify");
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("loading"),
                "SignedExchangeSignatureVerifier::Verify");
 

tools/metrics/histograms/histograms.xml

@@ -97642,6 +97642,16 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="SignedExchange.Time.SignatureVerify" units="ms"
+    expires_after="2019-10-01">
+  <owner>kinuko@chromium.org</owner>
+  <owner>kouhei@chromium.org</owner>
+  <summary>
+    The amount of time that elapsed during
+    SignedExchangeSignatureVerifier::Verify.
+  </summary>
+</histogram>
+
 <histogram name="SignedExchange.TimeUntilExpiration" units="seconds">
   <owner>kinuko@chromium.org</owner>
   <owner>kouhei@chromium.org</owner>