[Policy Experimental] Add "recommended" policies for URL exceptions.

components/policy/core/common/policy_map.h

Index: components/policy/core/common/policy_map.h
diff --git a/components/policy/core/common/policy_map.h b/components/policy/core/common/policy_map.h
index 9af8c53dee57075d9f82b5a8de97b167a61c4f7d..bd9d291d071db56f10e47f5e68c6e4f2b84265c3 100644
--- a/components/policy/core/common/policy_map.h
+++ b/components/policy/core/common/policy_map.h
@@ -49,23 +49,45 @@ class POLICY_EXPORT PolicyMap {
     bool Equals(const Entry& other) const;
   };
 
-  typedef std::map<std::string, Entry> PolicyMapType;
+  struct PolicyMapKey {
+    std::string name;
+
+    // POLICY_LEVEL_COUNT nominally has highest priority in PolicyLevel. Having
+    // this as default allows us to use lower_bound() to search by |name| only.
+    PolicyLevel level = POLICY_LEVEL_COUNT;
+
+    PolicyMapKey();
+
+    explicit PolicyMapKey(const std::string& name_in);
+
+    PolicyMapKey(const std::string& name_in, PolicyLevel level_in);
+
+    bool operator==(const PolicyMapKey& other) const;
+
+    bool operator<(const PolicyMapKey& other) const;
+
+    int compare(const PolicyMapKey& other) const;
+  };
+
+  typedef std::map<PolicyMapKey, Entry> PolicyMapType;
   typedef PolicyMapType::const_iterator const_iterator;
 
   PolicyMap();
   virtual ~PolicyMap();
 
-  // Returns a weak reference to the entry currently stored for key |policy|,
-  // or NULL if not found. Ownership is retained by the PolicyMap.
+  // Returns a weak reference to the highest priority entry currently stored
+  // for key |policy|, or null if not found. Ownership is retained by the
+  // PolicyMap.
   const Entry* Get(const std::string& policy) const;
 
-  // Returns a weak reference to the value currently stored for key |policy|,
-  // or NULL if not found. Ownership is retained by the PolicyMap.
-  // This is equivalent to Get(policy)->value, when it doesn't return NULL.
+  // Returns a weak reference to the highest priority entry currently stored
+  // under key |policy|, or null if not found. Ownership is retained by the
+  // PolicyMap.
+  // This is equivalent to Get(policy)->value, when it doesn't return null.
   const base::Value* GetValue(const std::string& policy) const;
 
   // Takes ownership of |value| and |external_data_fetcher|. Overwrites any
-  // existing information stored in the map for the key |policy|.
+  // existing information stored in the map for the key (|policy|, |level|).
   void Set(const std::string& policy,
            PolicyLevel level,
            PolicyScope scope,
@@ -73,7 +95,7 @@ class POLICY_EXPORT PolicyMap {
            base::Value* value,
            ExternalDataFetcher* external_data_fetcher);
 
-  // Erase the given |policy|, if it exists in this map.
+  // Erase all given |policy| that exists in this map.
   void Erase(const std::string& policy);
 
   // Swaps the internal representation of |this| with |other|.
@@ -85,6 +107,7 @@ class POLICY_EXPORT PolicyMap {
   // Returns a copy of |this|.
   scoped_ptr<PolicyMap> DeepCopy() const;
 
+  // TODO(huangs): Update comment.
   // Merges policies from |other| into |this|. Existing policies are only
   // overridden by those in |other| if they have a higher priority, as defined
   // by Entry::has_higher_priority_than(). If a policy is contained in both
@@ -104,7 +127,10 @@ class POLICY_EXPORT PolicyMap {
   // This includes keys that are present only in one of the maps.
   // |differing_keys| is not cleared before the keys are added.
   void GetDifferingKeys(const PolicyMap& other,
-                        std::set<std::string>* differing_keys) const;
+                        std::set<PolicyMapKey>* differing_keys) const;
+
+  void GetDifferingKeyNames(const PolicyMap& other,
+                            std::set<std::string>* differing_key_names) const;
 
   // Removes all policies that don't have the specified |level|. This is a
   // temporary helper method, until mandatory and recommended levels are served
@@ -118,6 +144,9 @@ class POLICY_EXPORT PolicyMap {
 
   const_iterator begin() const;
   const_iterator end() const;
+  void next_dominant(const_iterator* it) const;
+  void next_all(const_iterator* it) const;
+
   void Clear();
 
  private:
@@ -125,6 +154,10 @@ class POLICY_EXPORT PolicyMap {
   static bool MapEntryEquals(const PolicyMapType::value_type& a,
                              const PolicyMapType::value_type& b);
 
+  PolicyMapType::iterator lower_bound(const std::string& policy);
+
+  const_iterator lower_bound(const std::string& policy) const;
+
   PolicyMapType map_;
 
   DISALLOW_COPY_AND_ASSIGN(PolicyMap);