[Autofill] Add a new metric for upstream.

components/autofill/core/browser/autofill_metrics.h

Index: components/autofill/core/browser/autofill_metrics.h
diff --git a/components/autofill/core/browser/autofill_metrics.h b/components/autofill/core/browser/autofill_metrics.h
index b8e569baf697decbc73e158ec4996a1c81f7f1db..71c2e9abc9e3eff33980bef629c1a2fb7c9fb1cc 100644
--- a/components/autofill/core/browser/autofill_metrics.h
+++ b/components/autofill/core/browser/autofill_metrics.h
@@ -362,6 +362,8 @@ class AutofillMetrics {
     FORM_EVENT_LOCAL_SUGGESTION_FILLED_ONCE,
     FORM_EVENT_SERVER_SUGGESTION_FILLED_ONCE,
     FORM_EVENT_MASKED_SERVER_CARD_SUGGESTION_FILLED_ONCE,
+    // A dropdown with suggestions was shown and a form was submitted after that
+    FORM_EVENT_SUGGESTION_SHOWN_SUBMITTED_ONCE,

[Jared Saul, 2016/12/15 22:20:59]

Looks like this is a duplicate now; remove?

[Shanfeng, 2016/12/15 23:28:12]

Done.

     // A form was submitted. Depending on the user filling a local, server,
     // masked server card or no suggestion one of the following will be
     // triggered. Only one of the following four will be triggered per page
@@ -374,6 +376,12 @@ class AutofillMetrics {
     FORM_EVENT_MASKED_SERVER_CARD_SUGGESTION_SELECTED,
     // Same as above but only triggered once per page load.
     FORM_EVENT_MASKED_SERVER_CARD_SUGGESTION_SELECTED_ONCE,
+    // A dropdown with suggestions was shown and a form was submitted after that

[Jared Saul, 2016/12/15 22:20:59]

nit: s/that/that.
(for consistency; all the others end in a period)

[Shanfeng, 2016/12/15 23:28:12]

Done.

+    FORM_EVENT_SUGGESTION_SHOWN_SUBMITTED_ONCE,
+    // A dropdown with suggestions was shown and a form is about to be
+    // submitted. If the submission is not interrupted by JavaScript, the "form
+    // submitted" event above will also be logged.
+    FORM_EVENT_SUGGESTION_SHOWN_WILL_SUBMIT_ONCE,
     // An autofillable form is about to be submitted. If the submission is not
     // interrupted by JavaScript, the "form submitted" events above will also be
     // logged. Depending on the user filling a local, server, masked server card