Introduce a `ExclusionReasonsWithout` helper for ignoring reasons.

Change-Id: Ic2fdb5d1adb515af42735a7af1b563dd0aba8ed1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2540571
Commit-Queue: Chris Fredrickson <cfredric@chromium.org>
Reviewed-by: Lily Chen <chlily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827864}

net/cookies/cookie_inclusion_status.cc

@@ -21,8 +21,7 @@ uint32_t GetWarningBitmask(CookieInclusionStatus::WarningReason reason) {
 
 }  // namespace
 
-CookieInclusionStatus::CookieInclusionStatus()
-    : exclusion_reasons_(0u), warning_reasons_(0u) {}
+CookieInclusionStatus::CookieInclusionStatus() = default;
 
 CookieInclusionStatus::CookieInclusionStatus(ExclusionReason reason)
     : exclusion_reasons_(GetExclusionBitmask(reason)) {}
@@ -67,11 +66,20 @@ void CookieInclusionStatus::RemoveExclusionReason(ExclusionReason reason) {
   exclusion_reasons_ &= ~(GetExclusionBitmask(reason));
 }
 
+uint32_t CookieInclusionStatus::ExclusionReasonsWithout(
+    const std::vector<ExclusionReason>& reasons) const {
+  uint32_t mask = 0u;
+  for (const ExclusionReason reason : reasons) {
+    mask |= GetExclusionBitmask(reason);
+  }
+  return exclusion_reasons_ & ~mask;
+}
+
 void CookieInclusionStatus::MaybeClearSameSiteWarning() {
-  uint32_t samesite_reasons_mask =
-      GetExclusionBitmask(EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX) |
-      GetExclusionBitmask(EXCLUDE_SAMESITE_NONE_INSECURE);
-  if (exclusion_reasons_ & ~samesite_reasons_mask) {
+  if (ExclusionReasonsWithout({
+          EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX,
+          EXCLUDE_SAMESITE_NONE_INSECURE,
+      }) != 0u) {
     RemoveWarningReason(
         CookieInclusionStatus::WARN_SAMESITE_UNSPECIFIED_CROSS_SITE_CONTEXT);
     RemoveWarningReason(CookieInclusionStatus::WARN_SAMESITE_NONE_INSECURE);
@@ -79,11 +87,7 @@ void CookieInclusionStatus::MaybeClearSameSiteWarning() {
         CookieInclusionStatus::WARN_SAMESITE_UNSPECIFIED_LAX_ALLOW_UNSAFE);
   }
 
-  uint32_t context_reasons_mask =
-      GetExclusionBitmask(EXCLUDE_SAMESITE_STRICT) |
-      GetExclusionBitmask(EXCLUDE_SAMESITE_LAX) |
-      GetExclusionBitmask(EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX);
-  if (exclusion_reasons_ & ~context_reasons_mask) {
+  if (!ShouldRecordDowngradeMetrics()) {
     RemoveWarningReason(
         CookieInclusionStatus::WARN_STRICT_LAX_DOWNGRADE_STRICT_SAMESITE);
     RemoveWarningReason(
@@ -98,12 +102,11 @@ void CookieInclusionStatus::MaybeClearSameSiteWarning() {
 }
 
 bool CookieInclusionStatus::ShouldRecordDowngradeMetrics() const {
-  uint32_t context_reasons_mask =
-      GetExclusionBitmask(EXCLUDE_SAMESITE_STRICT) |
-      GetExclusionBitmask(EXCLUDE_SAMESITE_LAX) |
-      GetExclusionBitmask(EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX);
-
-  return (exclusion_reasons_ & ~context_reasons_mask) == 0u;
+  return ExclusionReasonsWithout({
+             EXCLUDE_SAMESITE_STRICT,
+             EXCLUDE_SAMESITE_LAX,
+             EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX,
+         }) == 0u;
 }
 
 bool CookieInclusionStatus::ShouldWarn() const {

net/cookies/cookie_inclusion_status.h

@@ -287,6 +287,10 @@ class NET_EXPORT CookieInclusionStatus {
       std::vector<WarningReason> warnings = std::vector<WarningReason>());
 
  private:
+  // Returns the `exclusion_reasons_` with the given `reasons` unset.
+  uint32_t ExclusionReasonsWithout(
+      const std::vector<ExclusionReason>& reasons) const;
+
   // A bit vector of the applicable exclusion reasons.
   uint32_t exclusion_reasons_ = 0u;
 

net/cookies/cookie_inclusion_status_unittest.cc

@@ -211,4 +211,44 @@ TEST(CookieInclusionStatusTest, HasDowngradeWarning) {
     EXPECT_EQ(warning, reason);
   }
 }
+
+TEST(CookieInclusionStatusTest, ShouldRecordDowngradeMetrics) {
+  EXPECT_TRUE(CookieInclusionStatus::MakeFromReasonsForTesting({})
+                  .ShouldRecordDowngradeMetrics());
+
+  EXPECT_TRUE(CookieInclusionStatus::MakeFromReasonsForTesting(
+                  {
+                      CookieInclusionStatus::EXCLUDE_SAMESITE_STRICT,
+                  })
+                  .ShouldRecordDowngradeMetrics());
+
+  EXPECT_TRUE(CookieInclusionStatus::MakeFromReasonsForTesting(
+                  {
+                      CookieInclusionStatus::EXCLUDE_SAMESITE_LAX,
+                  })
+                  .ShouldRecordDowngradeMetrics());
+
+  EXPECT_TRUE(CookieInclusionStatus::MakeFromReasonsForTesting(
+                  {
+                      CookieInclusionStatus::
+                          EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX,
+                  })
+                  .ShouldRecordDowngradeMetrics());
+
+  // Note: the following cases cannot occur under normal circumstances.
+  EXPECT_TRUE(CookieInclusionStatus::MakeFromReasonsForTesting(
+                  {
+                      CookieInclusionStatus::
+                          EXCLUDE_SAMESITE_UNSPECIFIED_TREATED_AS_LAX,
+                      CookieInclusionStatus::EXCLUDE_SAMESITE_LAX,
+                  })
+                  .ShouldRecordDowngradeMetrics());
+  EXPECT_FALSE(CookieInclusionStatus::MakeFromReasonsForTesting(
+                   {
+                       CookieInclusionStatus::EXCLUDE_SAMESITE_NONE_INSECURE,
+                       CookieInclusionStatus::EXCLUDE_SAMESITE_LAX,
+                   })
+                   .ShouldRecordDowngradeMetrics());
+}
+
 }  // namespace net