Convert enable_one_click_signin to new buildflag system

This flag is only used in a few places in Chrome

Review URL: https://codereview.chromium.org/1718093005

Cr-Original-Commit-Position: refs/heads/master@{#377038}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7a5d62652384fe38454e12f9559a518924124078
diff --git a/tools/gn/docs/cookbook.md b/tools/gn/docs/cookbook.md
index c328563..7b872d5 100644
--- a/tools/gn/docs/cookbook.md
+++ b/tools/gn/docs/cookbook.md
@@ -244,7 +244,7 @@
 | `enable_hidpi` (0/1)                    | `enable_hidpi` (true/false)                    | `//build/config/ui.gni`       |
 | `enable_managed_users` (0/1)            | `enable_managed_users` (true/false)            | `//build/config/features.gni` |
 | `enable_mdns` (0/1)                     | `enable_mdns` (true/false)                     | `//build/config/features.gni` |
-| `enable_one_click_signin` (0/1)         | `enable_one_click_signin` (true/false)         | `//build/config/features.gni` |
+| `enable_one_click_signin` (0/1)         | `enable_one_click_signin` (true/false)         | `//chrome/common/features.gni` |
 | `enable_pepper_cdms` (0/1)              | `enable_pepper_cdms` (true/false)              | `//build/config/features.gni` |
 | `enable_plugins` (0/1)                  | `enable_plugins` (true/false)                  | `//build/config/features.gni` |
 | `enable_plugin_installation` (0/1)      | `enable_plugin_installation` (true/false)      | `//build/config/features.gni` |