[Extensions Bindings] Allow for argument validation without conversion

extensions/renderer/api_signature.h

Index: extensions/renderer/api_signature.h
diff --git a/extensions/renderer/api_signature.h b/extensions/renderer/api_signature.h
index c2f3ab888749c7824f9c4c5e511a43621d2fb0d7..c9b120183cb5975256134be88cea7c581cf22fe7 100644
--- a/extensions/renderer/api_signature.h
+++ b/extensions/renderer/api_signature.h
@@ -30,32 +30,52 @@ class APISignature {
   APISignature(const base::ListValue& specification);
   ~APISignature();
 
+  // Parses |arguments| against this signature, and populates |args_out| with
+  // the v8 values (performing no conversion). The resulting vector may differ
+  // from the list of arguments passed in because it will include null-filled
+  // optional arguments.
+  // Returns true if the arguments were successfully parsed and converted.
+  bool ParseArgumentsToV8(gin::Arguments* arguments,
+                          const ArgumentSpec::RefMap& type_refs,
+                          std::vector<v8::Local<v8::Value>>* args_out,
+                          std::string* error) const;
+
   // Parses |arguments| against this signature, converting to a base::ListValue.
-  // If the arguments don't match, null is returned and |error| is populated.
-  std::unique_ptr<base::ListValue> ParseArguments(
-      gin::Arguments* arguments,
-      const ArgumentSpec::RefMap& type_refs,
-      v8::Local<v8::Function>* callback_out,
-      std::string* error) const;
+  // Returns true if the arguments were successfully parsed and converted, and
+  // populates |args_out| and |callback_out| with the JSON arguments and
+  // callback values, respectively. On failure, returns false populates |error|.
+  bool ParseArgumentsToJSON(gin::Arguments* arguments,
+                            const ArgumentSpec::RefMap& type_refs,
+                            std::unique_ptr<base::ListValue>* args_out,
+                            v8::Local<v8::Function>* callback_out,
+                            std::string* error) const;
 
  private:
+  // Common implementation for ParseArgumentsToJSON and ParseArgumentsToV8.
+  bool ParseArgumentsImpl(gin::Arguments* arguments,
+                          const ArgumentSpec::RefMap& type_refs,
+                          std::vector<v8::Local<v8::Value>>* v8_out,
+                          std::unique_ptr<base::ListValue>* json_out,
+                          v8::Local<v8::Function>* callback_out,
+                          std::string* error) const;
+
   // Attempts to match an argument from |arguments| to the given |spec|.
-  // If the next argmument does not match and |spec| is optional, a null
-  // base::Value is returned.
-  // If the argument matches, |arguments| is advanced and the converted value is
-  // returned.
-  // If the argument does not match and it is not optional, returns null and
-  // populates error.
-  std::unique_ptr<base::Value> ParseArgument(
-      const ArgumentSpec& spec,
-      v8::Local<v8::Context> context,
-      gin::Arguments* arguments,
-      const ArgumentSpec::RefMap& type_refs,
-      std::string* error) const;
+  // If the next argmument does not match and |spec| is optional, uses a null
+  // value.
+  // If the argument matches, |arguments| is advanced, and the matched value is
+  // added to either |v8_out| or |json_out|.
+  // Returns true on success.
+  bool ParseArgument(const ArgumentSpec& spec,
+                     v8::Local<v8::Context> context,
+                     gin::Arguments* arguments,
+                     const ArgumentSpec::RefMap& type_refs,
+                     std::vector<v8::Local<v8::Value>>* v8_out,
+                     base::ListValue* json_out,
+                     std::string* error) const;
 
   // Parses the callback from |arguments| according to |callback_spec|. Since
-  // the callback isn't converted into a base::Value, this is different from
-  // ParseArgument() above.
+  // the callback can be treated differently than the rest of the arguments,
+  // this differs from ParseArgument() above.
   bool ParseCallback(gin::Arguments* arguments,
                      const ArgumentSpec& callback_spec,
                      std::string* error,