[Autofill] Fix username suggestion display when field is already filled.

The problem was that the placeholder visibility was not updated in this
particular case. It used to be set when values were suggested for the
first time but usernames are filled in the page without a preview.

The placeholder's visibility is now updated everytime the view is
updated.

Bug: 777819
Change-Id: I9b85553f8186f05330207bd083e3fe7fb11395e9
Reviewed-on: https://chromium-review.googlesource.com/739794
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Roger McFarlane <rogerm@chromium.org>
Reviewed-by: Keishi Hattori <keishi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512554}

third_party/WebKit/LayoutTests/fast/forms/suggested-value-after-empty-suggested-value-expected.txt

@@ -87,7 +87,7 @@ Input after setting suggestedValue:
 |     <div>
 |       id="placeholder"
 |       pseudo="-internal-input-suggested"
-|       style="display: none !important;"
+|       style="display: block !important;"
 |       shadow:pseudoId="-internal-input-suggested"
 |       "suggested value"
 |     <div>

third_party/WebKit/LayoutTests/fast/forms/suggested-value-after-setvalue-expected.txt

@@ -10,7 +10,7 @@ After setting suggestedValue:
 |     <div>
 |       id="placeholder"
 |       pseudo="-internal-input-suggested"
-|       style="display: none !important;"
+|       style="display: block !important;"
 |       shadow:pseudoId="-internal-input-suggested"
 |       "suggested value"
 |     <div>

third_party/WebKit/LayoutTests/fast/forms/suggested-value-expected.txt

@@ -10,7 +10,7 @@ instead of "initial value".
 |     <div>
 |       id="placeholder"
 |       pseudo="-internal-input-suggested"
-|       style="display: none !important;"
+|       style="display: block !important;"
 |       shadow:pseudoId="-internal-input-suggested"
 |       "suggested value"
 |     <div>

third_party/WebKit/LayoutTests/platform/win7/fast/forms/suggested-value-expected.txt

@@ -10,7 +10,7 @@ instead of "initial value".
 |     <div>
 |       id="placeholder"
 |       pseudo="-internal-input-suggested"
-|       style="display: none !important;"
+|       style="display: block !important;"
 |       shadow:pseudoId="-internal-input-suggested"
 |       "suggested value"
 |     <div>

third_party/WebKit/Source/core/html/forms/TextFieldInputType.cpp

@@ -524,8 +524,6 @@ void TextFieldInputType::SpinButtonStepUp() {
 }
 
 void TextFieldInputType::UpdateView() {
-  // The suggested values are now shown using placeholder elements, so there is
-  // nothing to do here for the suggested values.
   if (GetElement().SuggestedValue().IsEmpty() &&
       GetElement().NeedsToUpdateViewValue()) {
     // Update the view only if needsToUpdateViewValue is true. It protects
@@ -535,8 +533,8 @@ void TextFieldInputType::UpdateView() {
     // updated. In this case, updateView() is called but we should not
     // update the view value.
     GetElement().SetInnerEditorValue(VisibleValue());
-    GetElement().UpdatePlaceholderVisibility();
   }
+  GetElement().UpdatePlaceholderVisibility();
 }
 
 void TextFieldInputType::FocusAndSelectSpinButtonOwner() {