Eliminate usage of PO2TS::GetPrimaryAccountID() in UbertokenFetcher.

chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc

Index: chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
diff --git a/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc b/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
index 2d7bac1f1d27dc5fcd9c0f53f8ed6441c71dee53..31c4b75bb316e90ca96731f20d3c2ea924b9933c 100644
--- a/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
+++ b/chrome/browser/extensions/api/identity/gaia_web_auth_flow.cc
@@ -8,6 +8,8 @@
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
+#include "chrome/browser/signin/profile_oauth2_token_service.h"
+#include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "google_apis/gaia/gaia_urls.h"
 #include "net/base/escape.h"
 
@@ -54,8 +56,10 @@ GaiaWebAuthFlow::~GaiaWebAuthFlow() {
 }
 
 void GaiaWebAuthFlow::Start() {
+  ProfileOAuth2TokenService* token_service =
+      ProfileOAuth2TokenServiceFactory::GetForProfile(profile_);
   ubertoken_fetcher_.reset(new UbertokenFetcher(profile_, this));
-  ubertoken_fetcher_->StartFetchingToken();
+  ubertoken_fetcher_->StartFetchingToken(token_service->GetPrimaryAccountId());
 }
 
 void GaiaWebAuthFlow::OnUbertokenSuccess(const std::string& token) {