Record UMA metrics for the new EduCoexistence flow

This CL records the error state of access token
fetch in the new EduCoexistence flow. The histogram
already exists and doesn't need to be defined.

Bug: 1140250
Change-Id: I2da00d0d01f273127aeb081737e00397fd19b735
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490732Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Kush Sinha <sinhak@chromium.org>
Commit-Queue: Yilkal Abe <yilkal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822255}

chrome/browser/ui/webui/chromeos/edu_coexistence_login_handler_chromeos.cc

@@ -53,6 +53,9 @@ constexpr char kEduCoexistenceLoginDefaultURL[] =
 constexpr char kOobe[] = "oobe";
 constexpr char kInSession[] = "in_session";
 
+constexpr char kFetchAccessTokenResultHistogram[] =
+    "AccountManager.EduCoexistence.FetchAccessTokenResult";
+
 signin::IdentityManager* GetIdentityManager() {
   Profile* profile = ProfileManager::GetActiveUserProfile();
   DCHECK(profile);
@@ -197,6 +200,9 @@ void EduCoexistenceLoginHandler::OnRefreshTokenUpdatedForAccount(
 void EduCoexistenceLoginHandler::OnOAuthAccessTokensFetched(
     GoogleServiceAuthError error,
     signin::AccessTokenInfo info) {
+  base::UmaHistogramEnumeration(kFetchAccessTokenResultHistogram, error.state(),
+                                GoogleServiceAuthError::NUM_STATES);
+
   if (error.state() != GoogleServiceAuthError::State::NONE) {
     // TODO(yilkal) call on to the ui to show error screen.
     return;