Reduce the number of CachedUAStyles

CachedUAStyles are large (160b) and not cheap to create because they
include several Length objects which have non-trivial destructors,
making CachedUAStyles expensive to destruct. This patch reduces the
number of CachedUAStyles by only creating them when needed.

There are two changes in this patch:
1) CachedUAStyle& is no longer a member on StyleAdjuster but is
instead passed in through StyleAdjuster::adjustRenderStyle.

2) The cached UA style is now constructed as-needed in
StyleResolverState::cacheUserAgentBorderAndBackground.
StyleResolverState always owned the CachedUAStyle but this patch
makes it explicit by changing the type to OwnPtr<CachedUAStyle>. A
null check was needed in RenderTheme::adjustStyle but otherwise
CachedUAStyle was not accessed without being set.

Before patch:
  facebook.com - 19,850 CachedUAStyles constructed
  wikipedia cat - 22,686 CachedUAStyles constructed

With patch:
  facebook.com - 538 CachedUAStyles constructed
  wikipedia cat - 16 CachedUAStyles constructed

Review URL: https://codereview.chromium.org/338673002

git-svn-id: svn://svn.chromium.org/blink/trunk@176163 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

@@ -194,7 +194,7 @@ static bool hasWillChangeThatCreatesStackingContext(const RenderStyle* style)
     return false;
 }
 
-void StyleAdjuster::adjustRenderStyle(RenderStyle* style, RenderStyle* parentStyle, Element *e)
+void StyleAdjuster::adjustRenderStyle(RenderStyle* style, RenderStyle* parentStyle, Element *e, const CachedUAStyle* cachedUAStyle)
 {
     ASSERT(parentStyle);
 
@@ -259,7 +259,7 @@ void StyleAdjuster::adjustRenderStyle(RenderStyle* style, RenderStyle* parentSty
 
     // Let the theme also have a crack at adjusting the style.
     if (style->hasAppearance())
-        RenderTheme::theme().adjustStyle(style, e, m_cachedUAStyle);
+        RenderTheme::theme().adjustStyle(style, e, cachedUAStyle);
 
     // If we have first-letter pseudo style, transitions, or animations, do not share this style.
     if (style->hasPseudoStyle(FIRST_LETTER) || style->transitions() || style->animations())

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.h

@@ -36,19 +36,17 @@ class RenderStyle;
 class StyleAdjuster {
     STACK_ALLOCATED();
 public:
-    StyleAdjuster(const CachedUAStyle& cachedUAStyle, bool useQuirksModeStyles)
-        : m_cachedUAStyle(cachedUAStyle)
-        , m_useQuirksModeStyles(useQuirksModeStyles)
+    StyleAdjuster(bool useQuirksModeStyles)
+        : m_useQuirksModeStyles(useQuirksModeStyles)
     { }
 
-    void adjustRenderStyle(RenderStyle* styleToAdjust, RenderStyle* parentStyle, Element*);
+    void adjustRenderStyle(RenderStyle* styleToAdjust, RenderStyle* parentStyle, Element*, const CachedUAStyle*);
 
 private:
     void adjustStyleForDisplay(RenderStyle* styleToAdjust, RenderStyle* parentStyle);
     void adjustStyleForTagName(RenderStyle* styleToAdjust, RenderStyle* parentStyle, Element&);
     void adjustOverflow(RenderStyle* styleToAdjust);
 
-    const CachedUAStyle& m_cachedUAStyle;
     bool m_useQuirksModeStyles;
 };
 

third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp

@@ -581,8 +581,8 @@ static void addContentAttrValuesToFeatures(const Vector<AtomicString>& contentAt
 
 void StyleResolver::adjustRenderStyle(StyleResolverState& state, Element* element)
 {
-    StyleAdjuster adjuster(state.cachedUAStyle(), m_document.inQuirksMode());
-    adjuster.adjustRenderStyle(state.style(), state.parentStyle(), element);
+    StyleAdjuster adjuster(m_document.inQuirksMode());
+    adjuster.adjustRenderStyle(state.style(), state.parentStyle(), element, state.cachedUAStyle());
 }
 
 // Start loading resources referenced by this style.

third_party/WebKit/Source/core/css/resolver/StyleResolverState.h

@@ -100,9 +100,14 @@ public:
         // and constructing it is expensive so we avoid it if possible.
         if (!style()->hasAppearance())
             return;
-        m_cachedUAStyle = CachedUAStyle(style());
+
+        m_cachedUAStyle = CachedUAStyle::create(style());
+    }
+
+    const CachedUAStyle* cachedUAStyle() const
+    {
+        return m_cachedUAStyle.get();
     }
-    const CachedUAStyle& cachedUAStyle() const { return m_cachedUAStyle; }
 
     ElementStyleResources& elementStyleResources() { return m_elementStyleResources; }
     const CSSToStyleMap& styleMap() const { return m_styleMap; }
@@ -150,7 +155,7 @@ private:
 
     FontBuilder m_fontBuilder;
 
-    CachedUAStyle m_cachedUAStyle;
+    OwnPtr<CachedUAStyle> m_cachedUAStyle;
 
     ElementStyleResources m_elementStyleResources;
     // CSSToStyleMap is a pure-logic class and only contains

third_party/WebKit/Source/core/rendering/RenderTheme.cpp

@@ -86,7 +86,7 @@ RenderTheme::RenderTheme()
 {
 }
 
-void RenderTheme::adjustStyle(RenderStyle* style, Element* e, const CachedUAStyle& uaStyle)
+void RenderTheme::adjustStyle(RenderStyle* style, Element* e, const CachedUAStyle* uaStyle)
 {
     // Force inline and table display styles to be inline-block (except for table- which is block)
     ControlPart part = style->appearance();
@@ -98,7 +98,7 @@ void RenderTheme::adjustStyle(RenderStyle* style, Element* e, const CachedUAStyl
     else if (style->display() == LIST_ITEM || style->display() == TABLE)
         style->setDisplay(BLOCK);
 
-    if (uaStyle.hasAppearance && isControlStyled(style, uaStyle)) {
+    if (uaStyle && uaStyle->hasAppearance && isControlStyled(style, uaStyle)) {
         if (part == MenulistPart) {
             style->setAppearance(MenulistButtonPart);
             part = MenulistButtonPart;
@@ -568,8 +568,10 @@ static bool isBackgroundOrBorderStyled(const RenderStyle& style, const CachedUAS
         || style.visitedDependentColor(CSSPropertyBackgroundColor) != uaStyle.backgroundColor;
 }
 
-bool RenderTheme::isControlStyled(const RenderStyle* style, const CachedUAStyle& uaStyle) const
+bool RenderTheme::isControlStyled(const RenderStyle* style, const CachedUAStyle* uaStyle) const
 {
+    ASSERT(uaStyle);
+
     switch (style->appearance()) {
     case PushButtonPart:
     case SquareButtonPart:
@@ -580,14 +582,14 @@ bool RenderTheme::isControlStyled(const RenderStyle* style, const CachedUAStyle&
     case ContinuousCapacityLevelIndicatorPart:
     case DiscreteCapacityLevelIndicatorPart:
     case RatingLevelIndicatorPart:
-        return isBackgroundOrBorderStyled(*style, uaStyle);
+        return isBackgroundOrBorderStyled(*style, *uaStyle);
 
     case ListboxPart:
     case MenulistPart:
     case SearchFieldPart:
     case TextAreaPart:
     case TextFieldPart:
-        return isBackgroundOrBorderStyled(*style, uaStyle) || style->boxShadow();
+        return isBackgroundOrBorderStyled(*style, *uaStyle) || style->boxShadow();
 
     case SliderHorizontalPart:
     case SliderVerticalPart:

third_party/WebKit/Source/core/rendering/RenderTheme.h

@@ -65,7 +65,7 @@ public:
     // metrics and defaults given the contents of the style.  This includes sophisticated operations like
     // selection of control size based off the font, the disabling of appearance when certain other properties like
     // "border" are set, or if the appearance is not supported by the theme.
-    void adjustStyle(RenderStyle*, Element*,  const CachedUAStyle&);
+    void adjustStyle(RenderStyle*, Element*, const CachedUAStyle*);
 
     // This method is called to paint the widget as a background of the RenderObject.  A widget's foreground, e.g., the
     // text of a button, is always rendered by the engine itself.  The boolean return value indicates
@@ -97,7 +97,7 @@ public:
     virtual bool controlSupportsTints(const RenderObject*) const { return false; }
 
     // Whether or not the control has been styled enough by the author to disable the native appearance.
-    virtual bool isControlStyled(const RenderStyle*, const CachedUAStyle&) const;
+    virtual bool isControlStyled(const RenderStyle*, const CachedUAStyle*) const;
 
     // A general method asking if any control tinting is supported at all.
     virtual bool supportsControlTints() const { return false; }

third_party/WebKit/Source/core/rendering/RenderThemeChromiumMac.h

@@ -44,7 +44,7 @@ public:
 
     virtual void adjustRepaintRect(const RenderObject*, IntRect&) OVERRIDE;
 
-    virtual bool isControlStyled(const RenderStyle*, const CachedUAStyle&) const OVERRIDE;
+    virtual bool isControlStyled(const RenderStyle*, const CachedUAStyle*) const OVERRIDE;
 
     virtual Color platformActiveSelectionBackgroundColor() const OVERRIDE;
     virtual Color platformInactiveSelectionBackgroundColor() const OVERRIDE;

third_party/WebKit/Source/core/rendering/RenderThemeChromiumMac.mm

@@ -510,10 +510,11 @@ Color RenderThemeChromiumMac::systemColor(CSSValueID cssValueId) const
     return color;
 }
 
-bool RenderThemeChromiumMac::isControlStyled(const RenderStyle* style, const CachedUAStyle& uaStyle) const
+bool RenderThemeChromiumMac::isControlStyled(const RenderStyle* style, const CachedUAStyle* uaStyle) const
 {
+    ASSERT(uaStyle);
     if (style->appearance() == TextFieldPart || style->appearance() == TextAreaPart || style->appearance() == ListboxPart)
-        return style->border() != uaStyle.border || style->boxShadow();
+        return style->border() != uaStyle->border || style->boxShadow();
 
     // FIXME: This is horrible, but there is not much else that can be done.  Menu lists cannot draw properly when
     // scaled.  They can't really draw properly when transformed either.  We can't detect the transform case at style

third_party/WebKit/Source/core/rendering/style/CachedUAStyle.h

@@ -32,12 +32,17 @@ namespace WebCore {
 // applyMatchedProperties for later use during adjustRenderStyle.
 class CachedUAStyle {
 public:
-    CachedUAStyle()
-        : hasAppearance(false)
-        , backgroundLayers(BackgroundFillLayer)
-        , backgroundColor(StyleColor::currentColor())
-    { }
+    static PassOwnPtr<CachedUAStyle> create(const RenderStyle* style)
+    {
+        return adoptPtr(new CachedUAStyle(style));
+    }
 
+    bool hasAppearance;
+    BorderData border;
+    FillLayer backgroundLayers;
+    StyleColor backgroundColor;
+
+private:
     explicit CachedUAStyle(const RenderStyle* style)
         : hasAppearance(true)
         , backgroundLayers(BackgroundFillLayer)
@@ -48,14 +53,10 @@ public:
         backgroundLayers = *style->backgroundLayers();
         backgroundColor = style->backgroundColor();
     }
-
-    bool hasAppearance;
-    BorderData border;
-    FillLayer backgroundLayers;
-    StyleColor backgroundColor;
 };
 
 
+
 } // namespace WebCore
 
 #endif // CachedUAStyle_h