Add histogram for SameParty cookies to log usage correctness

This adds a histogram to log, for SameParty cookies, whether the
attribute was applied correctly (i.e. whether the cookie both had Secure
and did not have SameSite=Strict).

Bug: 1142606
Change-Id: I512f0dd83896d917022ece0da2e85ac6f0d7392c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2510195Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Maksim Orlovich <morlovich@chromium.org>
Reviewed-by: Weilun Shi <sweilun@chromium.org>
Commit-Queue: Lily Chen <chlily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824009}

net/cookies/canonical_cookie.cc

@@ -50,6 +50,7 @@
 #include "base/feature_list.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/strcat.h"
 #include "base/strings/string_util.h"
@@ -416,6 +417,10 @@ std::unique_ptr<CanonicalCookie> CanonicalCookie::Create(
         CookieInclusionStatus::EXCLUDE_INVALID_SAMEPARTY);
   }
 
+  // Collect metrics on whether usage of SameParty attribute is correct.
+  if (parsed_cookie.IsSameParty())
+    base::UmaHistogramBoolean("Cookie.IsSamePartyValid", is_same_party_valid);
+
   // TODO(chlily): Log metrics.
   if (!status->IsInclude())
     return nullptr;

tools/metrics/histograms/histograms_xml/cookie/histograms.xml

@@ -162,6 +162,18 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram name="Cookie.IsSamePartyValid" enum="BooleanValid"
+    expires_after="2021-11-01">
+  <owner>chlily@chromium.org</owner>
+  <owner>kaustubhag@chromium.org</owner>
+  <summary>
+    If a cookie had the SameParty attribute, this histogram logs whether it was
+    used correctly (i.e., also had Secure and did not have SameSite=Strict).
+    Logged every time a cookie with SameParty is created from a string (i.e.
+    when it is set via Set-Cookie or document.cookie write).
+  </summary>
+</histogram>
+
 <histogram name="Cookie.KillDatabaseResult" enum="BooleanSuccess"
     expires_after="2020-11-08">
   <owner>morlovich@chromium.org</owner>