Reland of Change ScopedFeatureList to overrides FeatureList not reset

base/test/scoped_feature_list.cc

Index: base/test/scoped_feature_list.cc
diff --git a/base/test/scoped_feature_list.cc b/base/test/scoped_feature_list.cc
index f0f3f4edfba1f1d333ef3188836cf14273795739..22b20b96e034b8965e5ffdfdcb57daa1b86d9c84 100644
--- a/base/test/scoped_feature_list.cc
+++ b/base/test/scoped_feature_list.cc
@@ -4,22 +4,77 @@
 
 #include "base/test/scoped_feature_list.h"
 
+#include <algorithm>
 #include <string>
+#include <vector>
+
+#include "base/stl_util.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
 
 namespace base {
 namespace test {
 
 namespace {
 
-static std::string GetFeatureString(
+std::vector<StringPiece> GetFeatureVector(
     const std::initializer_list<base::Feature>& features) {
-  std::string output;
+  std::vector<StringPiece> output;
   for (const base::Feature& feature : features) {
-    if (!output.empty())
-      output += ",";
-    output += feature.name;
+    output.push_back(feature.name);
   }
+
   return output;
+}
+
+// Extracts a feature name from a feature state string. For example, given
+// the input "*MyLovelyFeature<SomeFieldTrial", returns "MyLovelyFeature".
+StringPiece GetFeatureName(StringPiece feature) {
+  StringPiece feature_name = feature;
+
+  // Remove default info.
+  if (feature_name.starts_with("*"))
+    feature_name = feature_name.substr(1);
+
+  // Remove field_trial info.
+  std::size_t index = feature_name.find("<");
+  if (index != std::string::npos)
+    feature_name = feature_name.substr(0, index);
+
+  return feature_name;
+}
+
+struct Features {
+  std::vector<StringPiece> enabled_feature_list;
+  std::vector<StringPiece> disabled_feature_list;
+};
+
+// Merges previously-specified feature overrides with those passed into one of
+// the Init() methods. |features| should be a list of features previously
+// overridden to be in the |override_state|. |merged_features| should contain
+// the enabled and disabled features passed into the Init() method, plus any
+// overrides merged as a result of previous calls to this function.
+void OverrideFeatures(const std::string& features,
+                      base::FeatureList::OverrideState override_state,
+                      Features* merged_features) {
+  std::vector<StringPiece> features_list =
+      SplitStringPiece(features, ",", TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
+
+  for (StringPiece feature : features_list) {
+    StringPiece feature_name = GetFeatureName(feature);
+
+    if (ContainsValue(merged_features->enabled_feature_list, feature_name) ||
+        ContainsValue(merged_features->disabled_feature_list, feature_name))
+      continue;
+
+    if (override_state == FeatureList::OverrideState::OVERRIDE_ENABLE_FEATURE) {
+      merged_features->enabled_feature_list.push_back(feature);
+    } else {
+      DCHECK_EQ(override_state,
+                FeatureList::OverrideState::OVERRIDE_DISABLE_FEATURE);
+      merged_features->disabled_feature_list.push_back(feature);
+    }
+  }
 }
 
 }  // namespace
@@ -40,13 +95,6 @@
   InitWithFeatureList(std::move(feature_list));
 }
 
-void ScopedFeatureList::InitWithFeatures(
-    const std::initializer_list<base::Feature>& enabled_features,
-    const std::initializer_list<base::Feature>& disabled_features) {
-  InitFromCommandLine(GetFeatureString(enabled_features),
-                      GetFeatureString(disabled_features));
-}
-
 void ScopedFeatureList::InitWithFeatureList(
     std::unique_ptr<FeatureList> feature_list) {
   DCHECK(!original_feature_list_);
@@ -62,12 +110,43 @@
   InitWithFeatureList(std::move(feature_list));
 }
 
+void ScopedFeatureList::InitWithFeatures(
+    const std::initializer_list<base::Feature>& enabled_features,
+    const std::initializer_list<base::Feature>& disabled_features) {
+  Features merged_features;
+  merged_features.enabled_feature_list = GetFeatureVector(enabled_features);
+  merged_features.disabled_feature_list = GetFeatureVector(disabled_features);
+
+  base::FeatureList* feature_list = base::FeatureList::GetInstance();
+
+  // |current_enabled_features| and |current_disabled_features| must declare out
+  // of if scope to avoid them out of scope before JoinString calls because
+  // |merged_features| may contains StringPiece which holding pointer points to
+  // |current_enabled_features| and |current_disabled_features|.
+  std::string current_enabled_features;
+  std::string current_disabled_features;
+  if (feature_list) {
+    base::FeatureList::GetInstance()->GetFeatureOverrides(
+        &current_enabled_features, &current_disabled_features);
+    OverrideFeatures(current_enabled_features,
+                     FeatureList::OverrideState::OVERRIDE_ENABLE_FEATURE,
+                     &merged_features);
+    OverrideFeatures(current_disabled_features,
+                     FeatureList::OverrideState::OVERRIDE_DISABLE_FEATURE,
+                     &merged_features);
+  }
+
+  std::string enabled = JoinString(merged_features.enabled_feature_list, ",");
+  std::string disabled = JoinString(merged_features.disabled_feature_list, ",");
+  InitFromCommandLine(enabled, disabled);
+}
+
 void ScopedFeatureList::InitAndEnableFeature(const base::Feature& feature) {
-  InitFromCommandLine(feature.name, std::string());
+  InitWithFeatures({feature}, {});
 }
 
 void ScopedFeatureList::InitAndDisableFeature(const base::Feature& feature) {
-  InitFromCommandLine(std::string(), feature.name);
+  InitWithFeatures({}, {feature});
 }
 
 }  // namespace test