Add support for multiple simultaneous subresource_filter::Configurations.

components/subresource_filter/core/browser/subresource_filter_features.h

Index: components/subresource_filter/core/browser/subresource_filter_features.h
diff --git a/components/subresource_filter/core/browser/subresource_filter_features.h b/components/subresource_filter/core/browser/subresource_filter_features.h
index c6106319cac4c7ab993d0b3b08c1a29f86f65257..db90ce237c785dd557be291e89be160656759e6b 100644
--- a/components/subresource_filter/core/browser/subresource_filter_features.h
+++ b/components/subresource_filter/core/browser/subresource_filter_features.h
@@ -5,6 +5,8 @@
 #ifndef COMPONENTS_SUBRESOURCE_FILTER_CORE_BROWSER_SUBRESOURCE_FILTER_FEATURES_H_
 #define COMPONENTS_SUBRESOURCE_FILTER_CORE_BROWSER_SUBRESOURCE_FILTER_FEATURES_H_
 
+#include <vector>
+
 #include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ -58,19 +60,31 @@ struct Configuration {
   bool should_whitelist_site_on_reload = false;
 };
 
-// TODO(engedy): Make this an actual list once all call sites are prepared to
-// handle multiple simultaneous configurations.
+// Thread-safe, ref-counted wrapper around an immutable list of configurations.
 class ConfigurationList : public base::RefCountedThreadSafe<ConfigurationList> {
  public:
+  explicit ConfigurationList(std::vector<Configuration> configs);
   explicit ConfigurationList(Configuration config);
 
-  const Configuration& the_one_and_only() const { return config_; }
+  // Returns the most specific ruleset flavor string that is prescribed by any
+  // of the configurations; where `most specific` is defined as the longest
+  // string, and in case of a tie, the lexicographically greatest among those.
+  std::string GetMostSpecificRulesetFlavor() const;
+
+  // Retrieves the configurations pre-sorted in decreasing order of priority.
+  //
+  // For each navigation, subresource filtering shall be activated according to
+  // at most one configuration: the one whose |activation_scope| contains the
+  // navigation, and has the highest priority among such configurations.
+  const std::vector<Configuration>& ordered_configs() const {
+    return ordered_configs_;
+  }
 
  private:
   friend class base::RefCountedThreadSafe<ConfigurationList>;
   ~ConfigurationList();
 
-  const Configuration config_;
+  const std::vector<Configuration> ordered_configs_;
 
   DISALLOW_COPY_AND_ASSIGN(ConfigurationList);
 };