SELECT element: Update menulist label when a user changes selection status

We missed to update textContent of a shadow node when
SelectMultipleOptionsByPopup() is called.
This issue affects only Android.

* html_select_element.cc:
  Update a shadow node content in |HTMLSelectElement::
  SelectMultipleOptionsByPopup()|.


* html_select_element_test.cc:
  Add a test case.

* test_blink_web_unit_test_support.cc:
  Fix a mock QueryLocalizedString() so that we can see different
  resultant strings depending on |value| argument.  The new behavior
  is similar to the QueryLocalizedString() implementation in production.

Bug: 1090247
Change-Id: I6d99e69dda6fc833eaa697daa304a8cd7a9d24ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2226581
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Auto-Submit: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774481}

content/test/test_blink_web_unit_test_support.cc

@@ -243,7 +243,7 @@ blink::WebString TestBlinkWebUnitTestSupport::QueryLocalizedString(
     case IDS_FORM_VALIDATION_RANGE_OVERFLOW:
       return blink::WebString::FromASCII("range overflow");
     case IDS_FORM_SELECT_MENU_LIST_TEXT:
-      return blink::WebString::FromASCII("$1 selected");
+      return blink::WebString::FromASCII(value.Ascii() + " selected");
   }
 
   return BlinkPlatformImpl::QueryLocalizedString(resource_id, value);

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

@@ -201,6 +201,7 @@ void HTMLSelectElement::SelectMultipleOptionsByPopup(
     }
   }
 
+  select_type_->UpdateTextStyleAndContent();
   SetNeedsValidityCheck();
   if (has_new_selection || !old_selection.IsEmpty()) {
     DispatchInputEvent();

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

@@ -50,6 +50,11 @@ class HTMLSelectElementTest : public PageTestBase {
     return select->isConnected();
   }
 
+  String MenuListLabel() const {
+    auto* select = To<HTMLSelectElement>(GetDocument().body()->firstChild());
+    return select->InnerElement().textContent();
+  }
+
  private:
   bool original_delegates_flag_;
 };
@@ -569,6 +574,16 @@ TEST_F(HTMLSelectElementTest, SelectMultipleOptionsByPopup) {
     EXPECT_FALSE(FirstSelectIsConnectedAfterSelectMultiple(Vector<int>{1}))
         << "Onchange handler should be executed.";
   }
+
+  // Check if the label is correctly updated.
+  {
+    SetHtmlInnerHTML(
+        "<select multiple>"
+        "<option selected>o0</option><option selected>o1</option></select>");
+    EXPECT_EQ("2 selected", MenuListLabel());
+    EXPECT_TRUE(FirstSelectIsConnectedAfterSelectMultiple(Vector<int>{1}));
+    EXPECT_EQ("o1", MenuListLabel());
+  }
 }
 
 TEST_F(HTMLSelectElementTest, IntrinsicInlineSizeOverflow) {