Extensions: Make it possible for permission parsing code to return a detailed error message.

extensions/common/permissions/api_permission_set.cc

Index: extensions/common/permissions/api_permission_set.cc
===================================================================
--- extensions/common/permissions/api_permission_set.cc	(revision 247036)
+++ extensions/common/permissions/api_permission_set.cc	(working copy)
@@ -41,10 +41,19 @@
       return false;
     }
 
-    if (!permission->FromValue(permission_value)) {
+    std::string error_details;
+    if (!permission->FromValue(permission_value, &error_details)) {
       if (error) {
-        *error = ErrorUtils::FormatErrorMessageUTF16(
-            errors::kInvalidPermission, permission_info->name());
+        if (error_details.empty()) {
+          *error = ErrorUtils::FormatErrorMessageUTF16(
+              errors::kInvalidPermission,
+              permission_info->name());
+        } else {
+          *error = ErrorUtils::FormatErrorMessageUTF16(
+              errors::kInvalidPermissionWithDetail,
+              permission_info->name(),
+              error_details);
+        }
         return false;
       }
       LOG(WARNING) << "Parse permission failed.";