Chromad: Add authentication flow

chrome/browser/chromeos/login/helper.h

Index: chrome/browser/chromeos/login/helper.h
diff --git a/chrome/browser/chromeos/login/helper.h b/chrome/browser/chromeos/login/helper.h
index f3ebd2fad49f6642e86bf32b9c3a79935dd58740..cd27dc773f406c356b6cb5c9acee4a50aa2882fd 100644
--- a/chrome/browser/chromeos/login/helper.h
+++ b/chrome/browser/chromeos/login/helper.h
@@ -108,6 +108,12 @@ content::StoragePartition* GetSigninPartition();
 // flow, the context of the sign-in webview storage partition is returned.
 net::URLRequestContextGetter* GetSigninContext();
 
+using OnPipeReadyCallback = base::Callback<void(base::ScopedFD fd)>;
+// Returns file descriptor of a pipe, open for reading. Pipe keeps the passed
+// data.
+void GetPipeReadEnd(const std::string& data,
+                    const OnPipeReadyCallback& callback);
+
 }  // namespace login
 
 }  // namespace chromeos