[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..557d28ac040bbeeca9932daa7e3647ff0f895c1d 100644
--- a/components/autofill/core/browser/autofill_metrics.h
+++ b/components/autofill/core/browser/autofill_metrics.h
@@ -363,9 +363,10 @@ class AutofillMetrics {
     FORM_EVENT_SERVER_SUGGESTION_FILLED_ONCE,
     FORM_EVENT_MASKED_SERVER_CARD_SUGGESTION_FILLED_ONCE,
     // 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
-    // load.
+    // masked server card or suggestion shown or no suggestion filled one of the
+    // following will be triggered. Only one of the following four will be
+    // triggered per page load.
+    FORM_EVENT_SUGGESTION_SHOWN_SUBMITTED_ONCE,

[Jared Saul, 2016/12/15 21:30:26]

FORM_EVENT_SUGGESTION_SHOWN_SUBMITTED_ONCE shouldn't go in this section, because
the other four events are mutually exclusive, whereas your new metric will
always happen if suggestions are shown and the form is submitted, regardless of
what the user picked.

[Shanfeng, 2016/12/15 21:59:03]

Done.

     FORM_EVENT_NO_SUGGESTION_SUBMITTED_ONCE,
     FORM_EVENT_LOCAL_SUGGESTION_SUBMITTED_ONCE,
     FORM_EVENT_SERVER_SUGGESTION_SUBMITTED_ONCE,
@@ -377,8 +378,9 @@ class AutofillMetrics {
     // 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
-    // or no suggestion one of the following will be triggered, at most once per
-    // page load.
+    // or suggestion shown or no suggestion filled one of the following will be
+    // triggered, at most once per page load.
+    FORM_EVENT_SUGGESTION_SHOWN_WILL_SUBMIT_ONCE,

[Jared Saul, 2016/12/15 21:30:26]

ditto

[Shanfeng, 2016/12/15 21:59:03]

Done.

     FORM_EVENT_NO_SUGGESTION_WILL_SUBMIT_ONCE,
     FORM_EVENT_LOCAL_SUGGESTION_WILL_SUBMIT_ONCE,
     FORM_EVENT_SERVER_SUGGESTION_WILL_SUBMIT_ONCE,