[chrome://flags] Let features override params in the same trial

components/flags_ui/feature_entry.h

Index: components/flags_ui/feature_entry.h
diff --git a/components/flags_ui/feature_entry.h b/components/flags_ui/feature_entry.h
index d61ba843815453bc18e98621b8aca998d36e9d5a..464488577481d6da46c23d2c85c25034001cdde1 100644
--- a/components/flags_ui/feature_entry.h
+++ b/components/flags_ui/feature_entry.h
@@ -147,7 +147,9 @@ struct FeatureEntry {
   const char* disable_command_line_switch;
   const char* disable_command_line_value;
 
-  // For FEATURE_VALUE, the base::Feature this entry corresponds to.
+  // For FEATURE_VALUE or FEATURE_WITH_VARIATIONS_VALUE, the base::Feature this
+  // entry corresponds to. The same feature must not be used in multiple
+  // FeatureEntries.
   const base::Feature* feature;
 
   // Number of options to choose from. This is used if type is MULTI_VALUE,
@@ -163,8 +165,9 @@ struct FeatureEntry {
   const FeatureVariation* feature_variations;
 
   // The name of the FieldTrial in which the selected variation parameters
-  // should be registered. This is used if type is
-  // FEATURE_WITH_VARIATIONS_VALUE.
+  // should be registered. Can be a nullptr if the parameters are accessed by
+  // their feature and the trial name is thus irrelevant. This is used if type
+  // is FEATURE_WITH_VARIATIONS_VALUE.
   const char* feature_trial_name;
 
   // Returns the name used in prefs for the option at the specified |index|.