Slightly simplify building FillLayer objects

Review URL: https://codereview.chromium.org/405093002

git-svn-id: svn://svn.chromium.org/blink/trunk@178546 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl

@@ -400,11 +400,8 @@ static bool lengthTypeAndValueMatch(const BorderImageLengthBox& borderImageLengt
     FillLayer* prevChild = 0;
     const FillLayer* currParent = &state.parentStyle()->{{layer_type|lower}}Layers();
     while (currParent && currParent->is{{fill_type}}Set()) {
-        if (!currChild) {
-            /* Need to make a new layer.*/
-            currChild = new FillLayer({{fill_layer_type}});
-            prevChild->setNext(currChild);
-        }
+        if (!currChild)
+            currChild = prevChild->ensureNext();
         currChild->set{{fill_type}}(currParent->{{fill_type|lower_first}}());
         prevChild = currChild;
         currChild = prevChild->next();
@@ -426,11 +423,8 @@ static bool lengthTypeAndValueMatch(const BorderImageLengthBox& borderImageLengt
         /* Walk each value and put it into a layer, creating new layers as needed. */
         CSSValueList* valueList = toCSSValueList(value);
         for (unsigned int i = 0; i < valueList->length(); i++) {
-            if (!currChild) {
-                /* Need to make a new layer to hold this value */
-                currChild = new FillLayer({{fill_layer_type}});
-                prevChild->setNext(currChild);
-            }
+            if (!currChild)
+                currChild = prevChild->ensureNext();
             state.styleMap().{{map_fill}}({{property_id}}, currChild, valueList->item(i));
             prevChild = currChild;
             currChild = currChild->next();

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

@@ -151,26 +151,8 @@ void setOnFillLayers(FillLayer& fillLayers, const AnimatableValue* value, StyleR
     FillLayer* fillLayer = &fillLayers;
     FillLayer* prev = 0;
     for (size_t i = 0; i < values.size(); ++i) {
-        if (!fillLayer) {
-            switch (property) {
-            case CSSPropertyBackgroundImage:
-            case CSSPropertyBackgroundPositionX:
-            case CSSPropertyBackgroundPositionY:
-            case CSSPropertyBackgroundSize:
-            case CSSPropertyWebkitBackgroundSize:
-                fillLayer = new FillLayer(BackgroundFillLayer);
-                break;
-            case CSSPropertyWebkitMaskImage:
-            case CSSPropertyWebkitMaskPositionX:
-            case CSSPropertyWebkitMaskPositionY:
-            case CSSPropertyWebkitMaskSize:
-                fillLayer = new FillLayer(MaskFillLayer);
-                break;
-            default:
-                ASSERT_NOT_REACHED();
-            }
-            prev->setNext(fillLayer);
-        }
+        if (!fillLayer)
+            fillLayer = prev->ensureNext();
         const AnimatableValue* layerValue = values[i].get();
         switch (property) {
         case CSSPropertyBackgroundImage:

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

@@ -84,6 +84,12 @@ public:
 
     const FillLayer* next() const { return m_next; }
     FillLayer* next() { return m_next; }
+    FillLayer* ensureNext()
+    {
+        if (!m_next)
+            m_next = new FillLayer(type());
+        return m_next;
+    }
 
     bool isImageSet() const { return m_imageSet; }
     bool isXPositionSet() const { return m_xPosSet; }
@@ -139,8 +145,6 @@ public:
     void clearSize() { m_sizeType = SizeNone; }
     void clearMaskSourceType() { m_maskSourceTypeSet = false; }
 
-    void setNext(FillLayer* n) { if (m_next != n) { delete m_next; m_next = n; } }
-
     FillLayer& operator=(const FillLayer& o);
     FillLayer(const FillLayer& o);