[DICE] Enable sync for an account that is already present in the token service.

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index 44c5cdd97e964fc588db245a1cd8e37f569709d2..221579bc3892005ef73bd82eca84795d69012d36 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -37,6 +37,7 @@
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "components/signin/core/browser/signin_metrics.h"
+#include "components/signin/core/common/profile_management_switches.h"
 #include "components/strings/grit/components_strings.h"
 #include "components/sync/base/bind_to_task_runner.h"
 #include "components/sync/base/cryptographer.h"
@@ -1961,6 +1962,14 @@ void ProfileSyncService::GoogleSigninSucceeded(const std::string& account_id,
     // Track the fact that we're still waiting for auth to complete.
     is_auth_in_progress_ = true;
   }
+
+  if (switches::IsAccountConsistencyDiceEnabled() &&
+      oauth2_token_service_->RefreshTokenIsAvailable(account_id)) {
+    // When Dice is enabled, the refresh token may be available before the user
+    // enables sync. Start sync if the refresh token is already available in the
+    // token service when the authenticated account is set.
+    OnRefreshTokenAvailable(account_id);

[Nicolas Zea, 2017/06/28 19:43:24]

Why isn't OnRefresTokenAvailable automatically being invoked by O2TS at the time
the user signs in? It seems odd to have to trigger this here.

[msarda2, 2017/06/28 19:58:30]

The problem is the order here: Take the following example with DICE enabled:
* On Monday, users starts Chrome and signs in to gmail. AT that moment, Chrome
will get a refresh token and will fire a OnRefreshTokenAvailable.
* Next Friday, the user decides to enable sync. At this point, SigninManager
fires GoogleSigninSucceeded. There is no OnRefreshTokenAvailable notification
being fired here as the token has not changed and has been around for 5 days
already.

The clients will need to be able to handle these events without making any
assumption of the order in which they arrive. This is why for sync, I need to
call OnRefreshTokenAvailable in this case.

I will update the design document with this explanation and with what we expect
clients to do to handle this correctly.

+  }
 }
 
 void ProfileSyncService::GoogleSignedOut(const std::string& account_id,