Revert "[Password Generation] Disable button titles calculation in Beta, Stable"

This reverts commit d0364f52.

Reason for revert: Branch point is over. Button titles should be re-enabled.

Original change's description:
> [Password Generation] Disable button titles calculation in Beta, Stable
>
> Button titles are not used in Beta, Stable channels at the moment. They will be crowdsourced later (as a part of crbug.com/896719).
> Button titles inference is expensive, especially, for <form>less forms. See the metric PasswordManager.ButtonTitlePerformance.NoFormTag. This will be fixed as a part of new parser refactoring.
> This CL temporarly disables button titles before branch point.
>
> Bug: 910546
> Change-Id: I55ac7d3bcbdc895e165cd3a46288fe089b558967
> Reviewed-on: https://chromium-review.googlesource.com/c/1432854
> Commit-Queue: Maxim Kolosovskiy <kolos@chromium.org>
> Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
> Auto-Submit: Maxim Kolosovskiy <kolos@chromium.org>
> Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#625600}

TBR=dvadym@chromium.org,kolos@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

TBR=dvadym@chromium.org

Bug: 910546
Change-Id: I16766fbd93ce627b5385965ce334f78c59a04631
Reviewed-on: https://chromium-review.googlesource.com/c/1437614
Commit-Queue: Maxim Kolosovskiy <kolos@chromium.org>
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Auto-Submit: Maxim Kolosovskiy <kolos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626251}

components/autofill/content/renderer/form_autofill_util.cc

@@ -1415,6 +1415,11 @@ bool UnownedFormElementsAndFieldSetsToFormData(
     FormData* form,
     FormFieldData* field) {
   form->origin = GetCanonicalOriginForDocument(document);
+  if (!document.Body().IsNull()) {
+    SCOPED_UMA_HISTOGRAM_TIMER(
+        "PasswordManager.ButtonTitlePerformance.NoFormTag");
+    form->button_titles = InferButtonTitlesForForm(document.Body());
+  }
   if (document.GetFrame() && document.GetFrame()->Top()) {
     form->main_frame_origin = document.GetFrame()->Top()->GetSecurityOrigin();
   } else {
@@ -1791,6 +1796,11 @@ bool WebFormElementToFormData(
   form->unique_renderer_id = form_element.UniqueRendererFormId();
   form->origin = GetCanonicalOriginForDocument(frame->GetDocument());
   form->action = GetCanonicalActionForForm(form_element);
+  {
+    SCOPED_UMA_HISTOGRAM_TIMER(
+        "PasswordManager.ButtonTitlePerformance.HasFormTag");
+    form->button_titles = InferButtonTitlesForForm(form_element);
+  }
   if (frame->Top()) {
     form->main_frame_origin = frame->Top()->GetSecurityOrigin();
   } else {