Add copy and assignment to FundamentalValue and StringValue.

base/values.cc

Index: base/values.cc
diff --git a/base/values.cc b/base/values.cc
index 0b0eb073e82348ff84d8925b62f6b1db2f118fad..459d56fa0222fa2ea98503ece9dd755022908725 100644
--- a/base/values.cc
+++ b/base/values.cc
@@ -174,7 +174,13 @@ bool Value::Equals(const Value* a, const Value* b) {
   return a->Equals(b);
 }
 
-Value::Value(Type type) : type_(type) {
+Value::Value(Type type) : type_(type) {}
+
+Value::Value(const Value& that) : type_(that.type_) {}
+
+Value& Value::operator=(const Value& that) {
+  type_ = that.type_;
+  return *this;
 }
 
 ///////////////////// FundamentalValue ////////////////////