Add metrics for schemes of content setting exceptions

components/content_settings/core/browser/host_content_settings_map.cc

Index: components/content_settings/core/browser/host_content_settings_map.cc
diff --git a/components/content_settings/core/browser/host_content_settings_map.cc b/components/content_settings/core/browser/host_content_settings_map.cc
index 1805e9cd1b74760f6b71f821e12adf3522e6d18c..20ce17a0ba1d5138b2c133ac5c0ac1c645ebf140 100644
--- a/components/content_settings/core/browser/host_content_settings_map.cc
+++ b/components/content_settings/core/browser/host_content_settings_map.cc
@@ -187,7 +187,7 @@ HostContentSettingsMap::HostContentSettingsMap(PrefService* prefs,
 
   MigrateKeygenSettings();
   MigrateDomainScopedSettings(false);
-  RecordNumberOfExceptions();
+  RecordExceptionMetrics();
 }
 
 // static
@@ -600,7 +600,7 @@ base::WeakPtr<HostContentSettingsMap> HostContentSettingsMap::GetWeakPtr() {
   return weak_ptr_factory_.GetWeakPtr();
 }
 
-void HostContentSettingsMap::RecordNumberOfExceptions() {
+void HostContentSettingsMap::RecordExceptionMetrics() {
   for (const content_settings::WebsiteSettingsInfo* info :
        *content_settings::WebsiteSettingsRegistry::GetInstance()) {
     ContentSettingsType content_type = info->type();
@@ -610,6 +610,15 @@ void HostContentSettingsMap::RecordNumberOfExceptions() {
     GetSettingsForOneType(content_type, std::string(), &settings);
     size_t num_exceptions = 0;
     for (const ContentSettingPatternSource& setting_entry : settings) {
+      // Skip default settings.
+      if (setting_entry.primary_pattern == ContentSettingsPattern::Wildcard() &&
+          setting_entry.secondary_pattern == ContentSettingsPattern::Wildcard())
+        continue;

[msramek, 2016/08/09 10:47:43]

nit: use braces {} if the if() takes more than one line

[lshang, 2016/08/10 04:32:35]

Done.

+
+      UMA_HISTOGRAM_ENUMERATION("ContentSettings.ExceptionScheme",
+                                setting_entry.primary_pattern.GetScheme(),
+                                ContentSettingsPattern::SCHEME_MAX);
+
       if (setting_entry.source == "preference")
         ++num_exceptions;
     }