Add scoped_ptr-safe base::Value to Dictionary/List conversion functions.

This change adds two static From() functions to the DictionaryValue and
ListValue classes which take a scoped_ptr to a Value and either convert
it to a scoped_ptr to a DictionaryValue or ListValue, or return nullptr.
These are intended to replace the existing pattern,

  make_scoped_ptr(static_cast<base::DictionaryValue*>(value.release()))

with the shorter and safer alternative,

  base::DictionaryValue::From(value.Pass())

Instances of this pattern in //extensions have been converted as
examples.

Review URL: https://codereview.chromium.org/1308013005

Cr-Commit-Position: refs/heads/master@{#348294}

1 files changed, 2 insertions, 10 deletions

diff --git a/extensions/browser/api_test_utils.cc b/extensions/browser/api_test_utils.cc
index 587f8e2..47bcb0e 100644
--- a/extensions/browser/api_test_utils.cc
+++ b/extensions/browser/api_test_utils.cc
@@ -24,11 +24,7 @@ scoped_ptr<base::Value> ParseJSON(const std::string& data) {
 }
 
 scoped_ptr<base::ListValue> ParseList(const std::string& data) {
-  scoped_ptr<base::Value> result = ParseJSON(data);
-  scoped_ptr<base::ListValue> list_result;
-  if (result->GetAsList(nullptr))
-    list_result.reset(static_cast<base::ListValue*>(result.release()));
-  return list_result;
+  return base::ListValue::From(ParseJSON(data));
 }
 
 // This helps us be able to wait until an UIThreadExtensionFunction calls
@@ -75,11 +71,7 @@ namespace extensions {
 namespace api_test_utils {
 
 scoped_ptr<base::DictionaryValue> ParseDictionary(const std::string& data) {
-  scoped_ptr<base::Value> result = ParseJSON(data);
-  scoped_ptr<base::DictionaryValue> dict_result;
-  if (result->GetAsDictionary(nullptr))
-    dict_result.reset(static_cast<base::DictionaryValue*>(result.release()));
-  return dict_result;
+  return base::DictionaryValue::From(ParseJSON(data));
 }
 
 bool GetBoolean(const base::DictionaryValue* val, const std::string& key) {