Retry: Make Isolated file system writable only if it is configured so

content/browser/child_process_security_policy_impl.cc

Index: content/browser/child_process_security_policy_impl.cc
diff --git a/content/browser/child_process_security_policy_impl.cc b/content/browser/child_process_security_policy_impl.cc
index 1f40966507ba86db4bed1cde61d4525a8233c2fb..90c0ead285327a2c6104ed7c88dc78a37b4955e9 100644
--- a/content/browser/child_process_security_policy_impl.cc
+++ b/content/browser/child_process_security_policy_impl.cc
@@ -399,6 +399,7 @@ void ChildProcessSecurityPolicyImpl::GrantReadFileSystem(
 
 void ChildProcessSecurityPolicyImpl::GrantReadWriteFileSystem(
     int child_id, const std::string& filesystem_id) {
+  fileapi::IsolatedContext::GetInstance()->SetWritable(filesystem_id, true);
   GrantPermissionsForFileSystem(child_id, filesystem_id,
                                 kReadFilePermissions |
                                 kWriteFilePermissions);