Added retry policy

chrome/browser/chromeos/login/enrollment/enrollment_screen.cc

Index: chrome/browser/chromeos/login/enrollment/enrollment_screen.cc
diff --git a/chrome/browser/chromeos/login/enrollment/enrollment_screen.cc b/chrome/browser/chromeos/login/enrollment/enrollment_screen.cc
index b752d4e61daf06870246a90520e41c1071b32fdf..b7713e88ad857302dff195a09232e564ffc7fa8d 100644
--- a/chrome/browser/chromeos/login/enrollment/enrollment_screen.cc
+++ b/chrome/browser/chromeos/login/enrollment/enrollment_screen.cc
@@ -64,9 +64,16 @@ EnrollmentScreen* EnrollmentScreen::Get(ScreenManager* manager) {
 
 EnrollmentScreen::EnrollmentScreen(BaseScreenDelegate* base_screen_delegate,
                                    EnrollmentScreenActor* actor)
-    : BaseScreen(base_screen_delegate),
-      actor_(actor),
-      weak_ptr_factory_(this) {}
+    : BaseScreen(base_screen_delegate), actor_(actor), weak_ptr_factory_(this) {

[joth, 2016/11/23 22:24:02]

as a general guide use initializer list when you can. so here:

, retry_backoff_(&retry_policy) {
  policy_.num_errors_to_ignore = 0; 
  ... // etc
}

[kumarniranjan, 2016/11/24 18:12:46]

Done.

+  policy_ = new net::BackoffEntry::Policy();
+  policy_->num_errors_to_ignore = 0;
+  policy_->initial_delay_ms = 4000;
+  policy_->multiply_factor = 2.0;

[joth, 2016/11/23 22:24:02]

given we're using this to paper over the TPM init, I'm inclined to have it not
multiply quite so quickly. suggest:
factor = 1.5 

[kumarniranjan, 2016/11/24 18:12:46]

Done.

+  policy_->jitter_factor = 0.1;
+  policy_->maximum_backoff_ms = -1;

[joth, 2016/11/23 22:24:03]

Lets cap the maximum delay to 8 minutes

[kumarniranjan, 2016/11/24 18:12:46]

Done.

+  policy_->entry_lifetime_ms = -1;
+  backoff_ = new net::BackoffEntry(policy_);
+}
 
 EnrollmentScreen::~EnrollmentScreen() {
   DCHECK(!enrollment_helper_ || g_browser_process->IsShuttingDown());
@@ -253,8 +260,17 @@ void EnrollmentScreen::OnEnrollmentError(policy::EnrollmentStatus status) {
       status.client_status() == policy::DM_STATUS_SERVICE_DEVICE_NOT_FOUND &&
       current_auth_ == AUTH_ATTESTATION && AdvanceToNextAuth())
     Show();
-  else
+  else {
     actor_->ShowEnrollmentStatus(status);
+    if (policy::DeviceCloudPolicyManagerChromeOS::
+            GetZeroTouchEnrollmentMode() ==
+        policy::ZeroTouchEnrollmentMode::HANDS_OFF) {
+      backoff_->InformOfRequest(false);
+      timer_.Start(FROM_HERE, backoff_->GetTimeUntilRelease(),
+                   base::Bind(&EnrollmentScreen::OnRetry,

[joth, 2016/11/23 22:24:02]

I don't have a strong preference, but it maybe clearer to make a new "DoRetry"
method that we call from here and from "OnRetry" as the latter is (AIUI?)
intended as a UI button click handler so it's misleading to call it from the
timer

It'd be also nice to log when the retry is happening and why (user button press
vs timer)

[kumarniranjan, 2016/11/24 18:12:46]

I agree. I ended up calling the method "ProcessRetry" instead of "DoRetry"

+                              weak_ptr_factory_.GetWeakPtr()));
+    }
+  }
 }
 
 void EnrollmentScreen::OnOtherError(
@@ -331,6 +347,7 @@ void EnrollmentScreen::SendEnrollmentAuthToken(const std::string& token) {
 }
 
 void EnrollmentScreen::ShowEnrollmentStatusOnSuccess() {
+  backoff_->InformOfRequest(true);
   if (elapsed_timer_)
     UMA_ENROLLMENT_TIME(kMetricEnrollmentTimeSuccess, elapsed_timer_);
   actor_->ShowEnrollmentStatus(policy::EnrollmentStatus::ForStatus(