New SELECT Popup: Very slow to open a popup with many items.

Source/web/PopupMenuImpl.cpp

Index: Source/web/PopupMenuImpl.cpp
diff --git a/Source/web/PopupMenuImpl.cpp b/Source/web/PopupMenuImpl.cpp
index 621fa5861f7ba0bfafd4e98ebfe7de003ec4a800..49fc55f0cd46bb413ecc41d3d2c2a98eafb8e5e2 100644
--- a/Source/web/PopupMenuImpl.cpp
+++ b/Source/web/PopupMenuImpl.cpp
@@ -27,6 +27,11 @@
 
 namespace blink {
 
+// We don't make child style information if the popup will have a lot of items
+// because of a performance problem.
+// TODO(tkent): This is a workaround.  We should do a performance optimization.
+static const unsigned styledChildrenLimit = 100;
+
 class PopupMenuCSSFontSelector : public CSSFontSelector {
 public:
     static PassRefPtrWillBeRawPtr<PopupMenuCSSFontSelector> create(Document* document, CSSFontSelector* ownerFontSelector)
@@ -94,13 +99,14 @@ void PopupMenuImpl::writeDocument(SharedBuffer* data)
         "window.dialogArguments = {\n", data);
     addProperty("selectedIndex", m_client->selectedIndex(), data);
     PagePopupClient::addString("children: [\n", data);
+    bool enableExtraStyling = ownerElement().countChildren() < styledChildrenLimit;
     for (HTMLElement& child : Traversal<HTMLElement>::childrenOf(ownerElement())) {
         if (isHTMLOptionElement(child))
-            addOption(toHTMLOptionElement(child), data);
+            addOption(toHTMLOptionElement(child), enableExtraStyling, data);
         if (isHTMLOptGroupElement(child))
-            addOptGroup(toHTMLOptGroupElement(child), data);
+            addOptGroup(toHTMLOptGroupElement(child), enableExtraStyling, data);
         if (isHTMLHRElement(child))
-            addSeparator(toHTMLHRElement(child), data);
+            addSeparator(toHTMLHRElement(child), enableExtraStyling, data);
     }
     PagePopupClient::addString("],\n", data);
     addProperty("anchorRectInScreen", anchorRectInScreen, data);
@@ -180,33 +186,35 @@ const char* fontStyleToString(FontStyle style)
     return 0;
 }
 
-void PopupMenuImpl::addElementStyle(HTMLElement& element, SharedBuffer* data)
+void PopupMenuImpl::addElementStyle(HTMLElement& element, bool enableExtraStyling, SharedBuffer* data)
 {
     const ComputedStyle* style = m_client->computedStyleForItem(element);
     ASSERT(style);
     PagePopupClient::addString("style: {\n", data);
-    addProperty("color", style->visitedDependentColor(CSSPropertyColor).serialized(), data);
-    addProperty("backgroundColor", style->visitedDependentColor(CSSPropertyBackgroundColor).serialized(), data);
-    const FontDescription& fontDescription = style->font().fontDescription();
-    addProperty("fontSize", fontDescription.computedPixelSize(), data);
-    addProperty("fontWeight", String(fontWeightToString(fontDescription.weight())), data);
-    PagePopupClient::addString("fontFamily: [\n", data);
-    for (const FontFamily* f = &fontDescription.family(); f; f = f->next()) {
-        addJavaScriptString(f->family().string(), data);
-        if (f->next())
-            PagePopupClient::addString(",\n", data);
-    }
-    PagePopupClient::addString("],\n", data);
-    addProperty("fontStyle", String(fontStyleToString(fontDescription.style())), data);
-    addProperty("fontVariant", String(fontVariantToString(fontDescription.variant())), data);
-    addProperty("visibility", String(style->visibility() == HIDDEN ? "hidden" : "visible"), data);
-    addProperty("display", String(style->display() == NONE ? "none" : "block"), data);
+    addProperty("visibility", String(style->visibility() == HIDDEN ? "hidden" : ""), data);
+    addProperty("display", String(style->display() == NONE ? "none" : ""), data);
     addProperty("direction", String(style->direction() == RTL ? "rtl" : "ltr"), data);
     addProperty("unicodeBidi", String(isOverride(style->unicodeBidi()) ? "bidi-override" : "normal"), data);
+    if (enableExtraStyling) {
+        addProperty("color", style->visitedDependentColor(CSSPropertyColor).serialized(), data);
+        addProperty("backgroundColor", style->visitedDependentColor(CSSPropertyBackgroundColor).serialized(), data);
+        const FontDescription& fontDescription = style->font().fontDescription();
+        addProperty("fontSize", fontDescription.computedPixelSize(), data);
+        addProperty("fontWeight", String(fontWeightToString(fontDescription.weight())), data);
+        PagePopupClient::addString("fontFamily: [\n", data);
+        for (const FontFamily* f = &fontDescription.family(); f; f = f->next()) {
+            addJavaScriptString(f->family().string(), data);
+            if (f->next())
+                PagePopupClient::addString(",\n", data);
+        }
+        PagePopupClient::addString("],\n", data);
+        addProperty("fontStyle", String(fontStyleToString(fontDescription.style())), data);
+        addProperty("fontVariant", String(fontVariantToString(fontDescription.variant())), data);
+    }
     PagePopupClient::addString("},\n", data);
 }
 
-void PopupMenuImpl::addOption(HTMLOptionElement& element, SharedBuffer* data)
+void PopupMenuImpl::addOption(HTMLOptionElement& element, bool enableExtraStyling, SharedBuffer* data)
 {
     PagePopupClient::addString("{\n", data);
     PagePopupClient::addString("type: \"option\",\n", data);
@@ -215,11 +223,11 @@ void PopupMenuImpl::addOption(HTMLOptionElement& element, SharedBuffer* data)
     addProperty("value", element.listIndex(), data);
     addProperty("ariaLabel", element.fastGetAttribute(HTMLNames::aria_labelAttr), data);
     addProperty("disabled", element.isDisabledFormControl(), data);
-    addElementStyle(element, data);
+    addElementStyle(element, enableExtraStyling, data);
     PagePopupClient::addString("},\n", data);
 }
 
-void PopupMenuImpl::addOptGroup(HTMLOptGroupElement& element, SharedBuffer* data)
+void PopupMenuImpl::addOptGroup(HTMLOptGroupElement& element, bool enableExtraStyling, SharedBuffer* data)
 {
     PagePopupClient::addString("{\n", data);
     PagePopupClient::addString("type: \"optgroup\",\n", data);
@@ -227,28 +235,28 @@ void PopupMenuImpl::addOptGroup(HTMLOptGroupElement& element, SharedBuffer* data
     addProperty("title", element.title(), data);
     addProperty("ariaLabel", element.fastGetAttribute(HTMLNames::aria_labelAttr), data);
     addProperty("disabled", element.isDisabledFormControl(), data);
-    addElementStyle(element, data);
+    addElementStyle(element, enableExtraStyling, data);
     PagePopupClient::addString("children: [", data);
     for (HTMLElement& child : Traversal<HTMLElement>::childrenOf(element)) {
         if (isHTMLOptionElement(child))
-            addOption(toHTMLOptionElement(child), data);
+            addOption(toHTMLOptionElement(child), enableExtraStyling, data);
         if (isHTMLOptGroupElement(child))
-            addOptGroup(toHTMLOptGroupElement(child), data);
+            addOptGroup(toHTMLOptGroupElement(child), enableExtraStyling, data);
         if (isHTMLHRElement(child))
-            addSeparator(toHTMLHRElement(child), data);
+            addSeparator(toHTMLHRElement(child), enableExtraStyling, data);
     }
     PagePopupClient::addString("],\n", data);
     PagePopupClient::addString("},\n", data);
 }
 
-void PopupMenuImpl::addSeparator(HTMLHRElement& element, SharedBuffer* data)
+void PopupMenuImpl::addSeparator(HTMLHRElement& element, bool enableExtraStyling, SharedBuffer* data)
 {
     PagePopupClient::addString("{\n", data);
     PagePopupClient::addString("type: \"separator\",\n", data);
     addProperty("title", element.title(), data);
     addProperty("ariaLabel", element.fastGetAttribute(HTMLNames::aria_labelAttr), data);
     addProperty("disabled", element.isDisabledFormControl(), data);
-    addElementStyle(element, data);
+    addElementStyle(element, enableExtraStyling, data);
     PagePopupClient::addString("},\n", data);
 }
 
@@ -354,13 +362,14 @@ void PopupMenuImpl::update()
     PagePopupClient::addString("window.updateData = {\n", data.get());
     PagePopupClient::addString("type: \"update\",\n", data.get());
     PagePopupClient::addString("children: [", data.get());
+    bool enableExtraStyling = ownerElement().countChildren() < styledChildrenLimit;
     for (HTMLElement& child : Traversal<HTMLElement>::childrenOf(ownerElement())) {
         if (isHTMLOptionElement(child))
-            addOption(toHTMLOptionElement(child), data.get());
+            addOption(toHTMLOptionElement(child), enableExtraStyling, data.get());
         if (isHTMLOptGroupElement(child))
-            addOptGroup(toHTMLOptGroupElement(child), data.get());
+            addOptGroup(toHTMLOptGroupElement(child), enableExtraStyling, data.get());
         if (isHTMLHRElement(child))
-            addSeparator(toHTMLHRElement(child), data.get());
+            addSeparator(toHTMLHRElement(child), enableExtraStyling, data.get());
     }
     PagePopupClient::addString("],\n", data.get());
     PagePopupClient::addString("}\n", data.get());