Make base::Value::TYPE a scoped enum.

base/values.h

Index: base/values.h
diff --git a/base/values.h b/base/values.h
index 21c3f5fb5cfcd64cc81569057c74f4b11d0cdafa..14a02e4077ea3ea7cad83a9ee1275360c033fbc1 100644
--- a/base/values.h
+++ b/base/values.h
@@ -49,15 +49,15 @@ class Value;
 // See the file-level comment above for more information.
 class BASE_EXPORT Value {
  public:
-  enum Type {
-    TYPE_NULL = 0,
-    TYPE_BOOLEAN,
-    TYPE_INTEGER,
-    TYPE_DOUBLE,
-    TYPE_STRING,
-    TYPE_BINARY,
-    TYPE_DICTIONARY,
-    TYPE_LIST
+  enum class Type {
+    NONE = 0,
+    BOOLEAN,
+    INTEGER,
+    DOUBLE,
+    STRING,
+    BINARY,
+    DICTIONARY,
+    LIST
     // Note: Do not add more types. See the file-level comment above for why.
   };
 
@@ -134,7 +134,7 @@ class BASE_EXPORT FundamentalValue : public Value {
   // Overridden from Value:
   bool GetAsBoolean(bool* out_value) const override;
   bool GetAsInteger(int* out_value) const override;
-  // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as
+  // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
   // doubles.
   bool GetAsDouble(double* out_value) const override;
   FundamentalValue* DeepCopy() const override;
@@ -287,7 +287,7 @@ class BASE_EXPORT DictionaryValue : public Value {
   // |out_value| is optional and will only be set if non-NULL.
   bool GetBoolean(StringPiece path, bool* out_value) const;
   bool GetInteger(StringPiece path, int* out_value) const;
-  // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as
+  // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
   // doubles.
   bool GetDouble(StringPiece path, double* out_value) const;
   bool GetString(StringPiece path, std::string* out_value) const;
@@ -427,7 +427,7 @@ class BASE_EXPORT ListValue : public Value {
   // |out_value| is optional and will only be set if non-NULL.
   bool GetBoolean(size_t index, bool* out_value) const;
   bool GetInteger(size_t index, int* out_value) const;
-  // Values of both type TYPE_INTEGER and TYPE_DOUBLE can be obtained as
+  // Values of both type Type::INTEGER and Type::DOUBLE can be obtained as
   // doubles.
   bool GetDouble(size_t index, double* out_value) const;
   bool GetString(size_t index, std::string* out_value) const;
@@ -562,6 +562,10 @@ BASE_EXPORT inline std::ostream& operator<<(std::ostream& out,
   return out << static_cast<const Value&>(value);
 }
 
+// Stream operator so that enum class Types can be used in log statements.
+BASE_EXPORT std::ostream& operator<<(std::ostream& out,
+                                     const Value::Type& type);
+
 }  // namespace base
 
 #endif  // BASE_VALUES_H_