Use std::unique_ptr to express ownership of base::Value in PolicyMap::Entry

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 9960531f64e1dea99dbb3baaaf922c44de7632e1..5b527adb867f7dace8ff37e9a3e30a7371bbd88f 100644
--- a/components/policy/core/common/policy_map.h
+++ b/components/policy/core/common/policy_map.h
@@ -28,19 +28,20 @@ class POLICY_EXPORT PolicyMap {
   struct POLICY_EXPORT Entry {
     PolicyLevel level;
     PolicyScope scope;
-    base::Value* value;
-    ExternalDataFetcher* external_data_fetcher;
+    std::unique_ptr<base::Value> value;
+    std::unique_ptr<ExternalDataFetcher> external_data_fetcher;

[dcheng, 2016/05/03 06:46:18]

These pointers logically own the values, so they ought to be std::unique_ptr.

 
     // For debugging and displaying only. Set by provider delivering the policy.
     PolicySource source;
 
     Entry();
+    ~Entry();
 
-    // Deletes all members owned by |this|.
-    void DeleteOwnedMembers();
+    Entry(Entry&&);
+    Entry& operator=(Entry&&);
 
     // Returns a copy of |this|.
-    std::unique_ptr<Entry> DeepCopy() const;
+    Entry DeepCopy() const;

[dcheng, 2016/05/03 06:46:18]

Since Entry is now movable, we may as well take advantage of it for DeepCopy(),
rather than indirecting through std::unique_ptr and then moving the result out.

This means we can write:
  map_entry = entry->DeepCopy();

Rather than:
  map_entry = std::move(*entry->DeepCopy());

 
     // Returns true if |this| has higher priority than |other|.
     bool has_higher_priority_than(const Entry& other) const;
@@ -64,14 +65,14 @@ class POLICY_EXPORT 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|.
+  // Overwrites any existing information stored in the map for the key |policy|.
   void Set(const std::string& policy,
            PolicyLevel level,
            PolicyScope scope,
            PolicySource source,
-           base::Value* value,
-           ExternalDataFetcher* external_data_fetcher);
+           std::unique_ptr<base::Value> value,
+           std::unique_ptr<ExternalDataFetcher> external_data_fetcher);
+  void Set(const std::string& policy, Entry entry);
 
   // Erase the given |policy|, if it exists in this map.
   void Erase(const std::string& policy);