Add metrics for schemes of content setting exceptions

components/content_settings/core/common/content_settings_pattern.cc

Index: components/content_settings/core/common/content_settings_pattern.cc
diff --git a/components/content_settings/core/common/content_settings_pattern.cc b/components/content_settings/core/common/content_settings_pattern.cc
index aa895948153c07fa1536be3d9346c80c9a2462c3..348892e5d1523be701aa21a356b6aab3c60cb8c3 100644
--- a/components/content_settings/core/common/content_settings_pattern.cc
+++ b/components/content_settings/core/common/content_settings_pattern.cc
@@ -21,6 +21,19 @@ namespace {
 // The component supports only one scheme for simplicity.
 const char* non_port_non_domain_wildcard_scheme = NULL;
 
+// Keep it consistent with enum SchemeType in content_settings_pattern.h.
+const char* const kSchemeNames[] = {
+  "wildcard",
+  "other",
+  url::kHttpScheme,
+  url::kHttpsScheme,
+  url::kFileScheme,
+  "chrome-extension",
+};
+
+static_assert(arraysize(kSchemeNames) == ContentSettingsPattern::SCHEME_MAX,
+              "kSchemeNames should have SCHEME_MAX elements");
+
 std::string GetDefaultPort(const std::string& scheme) {
   if (scheme == url::kHttpScheme)
     return "80";
@@ -590,6 +603,17 @@ std::string ContentSettingsPattern::ToString() const {
     return std::string();
 }
 
+ContentSettingsPattern::SchemeType ContentSettingsPattern::GetScheme() const {
+  if (parts_.is_scheme_wildcard)
+    return SCHEME_WILDCARD;
+
+  for (size_t i = 2; i < arraysize(kSchemeNames); ++i) {
+    if (parts_.scheme == kSchemeNames[i])
+      return static_cast<SchemeType>(i);
+  }
+  return SCHEME_OTHER;
+}
+
 ContentSettingsPattern::Relation ContentSettingsPattern::Compare(
     const ContentSettingsPattern& other) const {
   // Two invalid patterns are identical in the way they behave. They don't match