Pass Device ID in the oauth2/token request. Keep Device ID in local state on Chrome OS.

google_apis/gaia/fake_gaia.cc

Index: google_apis/gaia/fake_gaia.cc
diff --git a/google_apis/gaia/fake_gaia.cc b/google_apis/gaia/fake_gaia.cc
index bf2331d970abd5c8fcf42bd09cb9f1262ea6ff2d..7c9ff8c1d695b82d71466599861fc22c243d6f5d 100644
--- a/google_apis/gaia/fake_gaia.cc
+++ b/google_apis/gaia/fake_gaia.cc
@@ -602,6 +602,21 @@ void FakeGaia::HandleAuthToken(const HttpRequest& request,
       return;
     }
 
+    std::string device_id;
+    if (GetQueryParameter(request.content, "device_id", &device_id)) {
+      std::string device_type;
+      if (!GetQueryParameter(request.content, "device_type", &device_type)) {
+        http_response->set_code(net::HTTP_BAD_REQUEST);
+        LOG(ERROR) << "'device_type' should be set if 'device_id' is set.";
+        return;
+      }
+      if (device_type != "chrome") {
+        http_response->set_code(net::HTTP_BAD_REQUEST);
+        LOG(ERROR) << "'device_type' is not 'chrome'.";
+        return;
+      }
+    }
+
     base::DictionaryValue response_dict;
     response_dict.SetString("refresh_token",
                             merge_session_params_.refresh_token);