[AF] Remove yellow backgroung on input field when site resets it.

Bug: 839859
Change-Id: I198b4cf906ed1eabb250c56282b34d96dbd53415
Reviewed-on: https://chromium-review.googlesource.com/1045174Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556772}

components/autofill/content/renderer/password_autofill_agent.cc

@@ -729,8 +729,10 @@ void PasswordAutofillAgent::PasswordValueGatekeeper::Reset() {
 
 void PasswordAutofillAgent::PasswordValueGatekeeper::ShowValue(
     blink::WebInputElement* element) {
-  if (!element->IsNull() && !element->SuggestedValue().IsEmpty())
+  if (!element->IsNull() && !element->SuggestedValue().IsEmpty()) {
     element->SetAutofillValue(element->SuggestedValue());
+    element->SetAutofilled(true);
+  }
 }
 
 bool PasswordAutofillAgent::TextDidChangeInTextField(

third_party/WebKit/LayoutTests/fast/forms/text/input-appearance-autofill-after-js-reset-expected.html

+<input id="input" value="" style="width: 99px">
\ No newline at end of file

third_party/WebKit/LayoutTests/fast/forms/text/input-appearance-autofill-after-js-reset.html

+<input id="input" >
+<script>
+input.focus();
+internals.setAutofilledValue(input, 'Springfield');
+input.style.width = '99px';
+input.blur();
+input.value = "";
+</script>

third_party/blink/renderer/core/html/forms/html_input_element.cc

@@ -1123,6 +1123,10 @@ void HTMLInputElement::setValue(const String& value,
   // update.
   TextControlElement::SetSuggestedValue(String());
 
+  // Set autofilled to false, as the value might have been set by the website.
+  // If the field was autofilled, it'll be set to true from that method.
+  SetAutofilled(false);
+
   EventQueueScope scope;
   String sanitized_value = SanitizeValue(value);
   bool value_changed = sanitized_value != this->value();