SELECT popup: Fix OPTGROUP rendering on a device with a touch-screen.

third_party/WebKit/Source/web/PopupMenuImpl.cpp

Index: third_party/WebKit/Source/web/PopupMenuImpl.cpp
diff --git a/third_party/WebKit/Source/web/PopupMenuImpl.cpp b/third_party/WebKit/Source/web/PopupMenuImpl.cpp
index 5186a47f77fde5c402c122d0396ba40f4e8f9ce9..863ebc69d49eb5388fb2193a01a1e43a049b8d71 100644
--- a/third_party/WebKit/Source/web/PopupMenuImpl.cpp
+++ b/third_party/WebKit/Source/web/PopupMenuImpl.cpp
@@ -275,6 +275,8 @@ void PopupMenuImpl::WriteDocument(SharedBuffer* data) {
   PagePopupClient::AddString(String::Format("option, optgroup {"
                                             "padding-top: %dpx;"
                                             "padding-bottom: %dpx;"

[keishi, 2017/04/18 05:45:49]

Do we want to add a padding below optgroup, after all the options?
I think these style properties(including the ones below) needed to be applied to
the optgroup-label shadow element.

[tkent, 2017/04/18 06:04:49]

You're right, padding-bottom isn't necessary. I think we want padding-top
though.
That's right. However, I had no good idea to apply these properties only in
popups. We don't want to change the behavior of in-page listboxes.

+                                            "}\n"
+                                            "option {"
                                             "min-height: %dpx;"
                                             "display: flex;"
                                             "align-items: center;"