[Autofill] Add FormEvent logging for "will submit form".

components/autofill/core/browser/autofill_metrics.cc

Index: components/autofill/core/browser/autofill_metrics.cc
diff --git a/components/autofill/core/browser/autofill_metrics.cc b/components/autofill/core/browser/autofill_metrics.cc
index 57716f24441c8b656d00eb22bfc6184f468f26ab..1cdb877917e5d8ed0bafa7a3481ff602dc47388a 100644
--- a/components/autofill/core/browser/autofill_metrics.cc
+++ b/components/autofill/core/browser/autofill_metrics.cc
@@ -522,9 +522,10 @@ AutofillMetrics::FormEventLogger::FormEventLogger(bool is_for_credit_card)
       has_logged_suggestions_shown_(false),
       has_logged_masked_server_card_suggestion_selected_(false),
       has_logged_suggestion_filled_(false),
+      has_logged_will_submit_(false),
       has_logged_submitted_(false),
       logged_suggestion_filled_was_server_data_(false),
-      logged_suggestion_filled_was_masked_server_card_(false) {};
+      logged_suggestion_filled_was_masked_server_card_(false){};

[Ilya Sherman, 2015/03/23 20:58:16]

nit: Please revert the diff on this line.  Also, while you're here, please drop
the semicolon on this line.

[Mathieu, 2015/03/23 21:11:28]

This is the work of "git cl format" but removing the semi-colon makes it nice
again.

 
 void AutofillMetrics::FormEventLogger::OnDidInteractWithAutofillableForm() {
   if (!has_logged_interacted_) {
@@ -597,7 +598,20 @@ void AutofillMetrics::FormEventLogger::OnDidFillSuggestion(
   }
 }
 
-void AutofillMetrics::FormEventLogger::OnDidSubmitForm() {
+void AutofillMetrics::FormEventLogger::OnWillSubmitForm() {
+  // Not logging this kind of form if we haven't logged a user interaction.
+  if (!has_logged_interacted_)
+    return;
+
+  // Not logging twice.
+  if (has_logged_will_submit_)
+    return;
+  has_logged_will_submit_ = true;
+
+  Log(AutofillMetrics::FORM_EVENT_WILL_SUBMIT_ONCE);

[Ilya Sherman, 2015/03/23 20:58:16]

Do we want to split up the WILL_SUBMIT_* metrics the same way we do the
SUBMITTED_* ones?  For some forms, we'll only see the "WILL_SUBMIT" metrics,
right?

[Mathieu, 2015/03/23 21:11:28]

Yes some forms will only emit WILL_SUBMIT_ONCE. I don't know, I'm not sure I am
after the same analysis as Walter was when he did OnFormSubmitted... I guess I
could add it for parity? 

[Ilya Sherman, 2015/03/23 23:58:17]

I defer to Walter and Evan, but it does seem likely that the same data would be
useful for AJAX-powered forms as for others.

+}
+
+void AutofillMetrics::FormEventLogger::OnFormSubmitted() {
   // Not logging this kind of form if we haven't logged a user interaction.
   if (!has_logged_interacted_)
     return;