Added a validator for JSON v3 schemas.

chrome/common/json_schema/json_schema_constants.h

Index: chrome/common/json_schema/json_schema_constants.h
diff --git a/chrome/common/json_schema/json_schema_constants.h b/chrome/common/json_schema/json_schema_constants.h
index fa4b80bfc0bcb052f65ddde8126d087c71ad19cd..1ca6a94d41652632ffdea27661a6e742d941efeb 100644
--- a/chrome/common/json_schema/json_schema_constants.h
+++ b/chrome/common/json_schema/json_schema_constants.h
@@ -13,6 +13,7 @@ extern const char kAny[];
 extern const char kArray[];
 extern const char kBoolean[];
 extern const char kChoices[];
+extern const char kDescription[];
 extern const char kEnum[];
 extern const char kId[];
 extern const char kInteger[];
@@ -28,9 +29,12 @@ extern const char kNumber[];
 extern const char kObject[];
 extern const char kOptional[];
 extern const char kPattern[];
+extern const char kPatternProperties[];
 extern const char kProperties[];
 extern const char kRef[];
+extern const char kSchema[];
 extern const char kString[];
+extern const char kTitle[];
 extern const char kType[];
 
 }  // namespace json_schema_constants