Integrate external mount points to IsolatedContext

content/browser/fileapi/fileapi_message_filter.cc

Index: content/browser/fileapi/fileapi_message_filter.cc
diff --git a/content/browser/fileapi/fileapi_message_filter.cc b/content/browser/fileapi/fileapi_message_filter.cc
index da6581b5d4d5a24abe3222a91f9a8374afa1a445..ca59679e48f205890b20b70e3551ddf6c8336e09 100644
--- a/content/browser/fileapi/fileapi_message_filter.cc
+++ b/content/browser/fileapi/fileapi_message_filter.cc
@@ -755,10 +755,10 @@ bool FileAPIMessageFilter::HasPermissionsForFile(
   ChildProcessSecurityPolicyImpl* policy =
       ChildProcessSecurityPolicyImpl::GetInstance();
 
-  // Special handling for filesystems which have isolated filesystem_id.
+  // Special handling for filesystems whose mount type is isolated.
   // (See ChildProcessSecurityPolicy::GrantReadFileSystem for more
   // details about access permission for isolated filesystem.)
-  if (!url.filesystem_id().empty()) {
+  if (url.mount_type() == fileapi::kFileSystemMountTypeIsolated) {
     // The root directory of the dragged filesystem is read-only.
     if (url.type() == fileapi::kFileSystemTypeDragged && url.path().empty()) {
       if (permissions != kReadFilePermissions) {