Google OAuth Device Flow support for FNL

mojo/services/authentication/interfaces/authentication.mojom

Index: mojo/services/authentication/interfaces/authentication.mojom
diff --git a/mojo/services/authentication/interfaces/authentication.mojom b/mojo/services/authentication/interfaces/authentication.mojom
index cc2a6f8a58fcf0667b1fa9e37c15f657f29a8839..ab12843aebcb75688aca9068205566bbf9a39645 100644
--- a/mojo/services/authentication/interfaces/authentication.mojom
+++ b/mojo/services/authentication/interfaces/authentication.mojom
@@ -18,7 +18,7 @@ interface AuthenticationService {
   SelectAccount(bool return_last_selected) => (string? username, string? error);
 
   // Requests an oauth2 token for the given Google account with the given
-  // scopes.  In case of error, username will be null and error will contain a
+  // scopes.  In case of error, token will be null and error will contain a
   // description of the error.
   GetOAuth2Token(string username, array<string> scopes) =>
       (string? token, string? error);
@@ -27,4 +27,15 @@ interface AuthenticationService {
   // token is refused by a server component before requesting a new token to
   // clear the token from any cache.
   ClearOAuth2Token(string token);
+
+  // Requests an oauth2 device code response for the given set of scopes. In

[rudominer, 2015/12/17 07:28:30]

I think you need more comments that explain how to use these methods. If I
understand correctly, the combination of GetOAuth2DeviceCode() followed by
AddAccount() is to be used instead of using SelectAccount() when running on FNL.
SelectAccount() should only be used when running on Android and these two
methods should only be used when not running on Android. Is that right? If that
is not right please explain the relationship between the methods.

[ukode, 2015/12/17 21:53:24]

Thats right. Fixed the comments.

+  // case of error, response will be null and error will contain a description

[rudominer, 2015/12/17 07:28:30]

s/response will be null/verifcation_url, device_code and user_code will be null/
or "all response parameters other than error will be null"

[ukode, 2015/12/17 21:53:24]

Done.

+  // of the error.
+  GetOAuth2DeviceCode(array<string> scopes) => (string? verification_url, string? device_code, string? user_code, string? error);

[rudominer, 2015/12/17 07:28:30]

break long line please.

[ukode, 2015/12/17 21:53:24]

Done.

+
+  // Exchanges an oauth2 device code to a refresh token for the granted user,
+  // and stores it locally in a secure storage location. For future
+  // GetOAuth2Token requests, a new access token is minted from this refresh
+  // token and returned to the calling mojo app.
+  AddAccount(string device_code) => (string? username, string? error);
 };