Simplify some Length comparisons with 'auto'

Using Length::IsAuto() is more efficient (and generates significantly
less code) than constructing a new Length and comparing with that.

Also replace some open-coded "is auto" checks with said method, and
simplify the surrounding code a bit.

Change-Id: I974a28a0eef969b56557428eb019f7cf1dac18c1
Reviewed-on: https://chromium-review.googlesource.com/806170Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#521456}

third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp

@@ -710,10 +710,10 @@ static CSSValue* ValueForLineHeight(const ComputedStyle& style) {
 
 static CSSValue* ValueForPosition(const LengthPoint& position,
                                   const ComputedStyle& style) {
-  DCHECK((position.X() == kAuto) == (position.Y() == kAuto));
-  if (position.X() == kAuto) {
+  DCHECK_EQ(position.X().IsAuto(), position.Y().IsAuto());
+  if (position.X().IsAuto())
     return CSSIdentifierValue::Create(CSSValueAuto);
-  }
+
   CSSValueList* list = CSSValueList::CreateSpaceSeparated();
   list->Append(*ZoomAdjustedPixelValueForLength(position.X(), style));
   list->Append(*ZoomAdjustedPixelValueForLength(position.Y(), style));

third_party/WebKit/Source/core/layout/LayoutBlockFlowLine.cpp

@@ -1500,11 +1500,12 @@ LayoutObject* InlineMinMaxIterator::Next() {
   return current;
 }
 
-static LayoutUnit GetBPMWidth(LayoutUnit child_value, Length css_unit) {
-  if (css_unit.GetType() != kAuto)
-    return (css_unit.IsFixed() ? static_cast<LayoutUnit>(css_unit.Value())
-                               : child_value);
-  return LayoutUnit();
+static LayoutUnit GetBPMWidth(LayoutUnit child_value, const Length& css_unit) {
+  if (css_unit.IsFixed())
+    return LayoutUnit(css_unit.Value());
+  if (css_unit.IsAuto())
+    return LayoutUnit();
+  return child_value;
 }
 
 static LayoutUnit GetBorderPaddingMargin(const LayoutBoxModelObject& child,

third_party/WebKit/Source/core/layout/LayoutDeprecatedFlexibleBox.cpp

@@ -1356,17 +1356,18 @@ LayoutUnit LayoutDeprecatedFlexibleBox::AllowedChildFlex(LayoutBox* child,
   if (IsHorizontal()) {
     LayoutUnit min_width = child->MinPreferredLogicalWidth();
     LayoutUnit width = ContentWidthForChild(child);
-    if (child->Style()->MinWidth().IsFixed())
-      min_width = LayoutUnit(child->Style()->MinWidth().Value());
-    else if (child->Style()->MinWidth().GetType() == kAuto)
+    const Length& min_width_length = child->Style()->MinWidth();
+    if (min_width_length.IsFixed())
+      min_width = LayoutUnit(min_width_length.Value());
+    else if (min_width_length.IsAuto())
       min_width = LayoutUnit();
 
     LayoutUnit allowed_shrinkage = (min_width - width).ClampPositiveToZero();
     return allowed_shrinkage;
   }
-  Length min_height = child->Style()->MinHeight();
-  if (min_height.IsFixed() || min_height.IsAuto()) {
-    LayoutUnit min_height(child->Style()->MinHeight().Value());
+  const Length& min_height_length = child->Style()->MinHeight();
+  if (min_height_length.IsFixed() || min_height_length.IsAuto()) {
+    LayoutUnit min_height(min_height_length.Value());
     LayoutUnit height = ContentHeightForChild(child);
     LayoutUnit allowed_shrinkage = (min_height - height).ClampPositiveToZero();
     return allowed_shrinkage;

third_party/WebKit/Source/core/layout/TableLayoutAlgorithmFixed.cpp

@@ -167,7 +167,7 @@ int TableLayoutAlgorithmFixed::CalcWidthArray() {
     while (used_span < span && current_column < n_eff_cols) {
       float e_span = table_->SpanOfEffectiveColumn(current_column);
       // Only set if no col element has already set it.
-      if (width_[current_column].IsAuto() && logical_width.GetType() != kAuto) {
+      if (width_[current_column].IsAuto() && !logical_width.IsAuto()) {
         width_[current_column] = logical_width;
         width_[current_column] *= e_span / span;
         used_width += fixed_border_box_logical_width * e_span / span;

third_party/WebKit/Source/core/style/ComputedStyle.cpp

@@ -1011,9 +1011,9 @@ void ComputedStyle::ApplyMotionPathTransform(
 
   float origin_shift_x = 0;
   float origin_shift_y = 0;
-  // If offset-Position and offset-anchor properties are not yet enabled,
+  // If the offset-position and offset-anchor properties are not yet enabled,
   // they will have the default value, auto.
-  if (position.X() != Length(kAuto) || anchor.X() != Length(kAuto)) {
+  if (!position.X().IsAuto() || !anchor.X().IsAuto()) {
     // Shift the origin from transform-origin to offset-anchor.
     origin_shift_x =
         FloatValueForLength(anchor.X(), bounding_box.Width()) -
@@ -1027,7 +1027,7 @@ void ComputedStyle::ApplyMotionPathTransform(
                       point.Y() - origin_y + origin_shift_y);
   transform.Rotate(angle + rotate.angle);
 
-  if (position.X() != Length(kAuto) || anchor.X() != Length(kAuto))
+  if (!position.X().IsAuto() || !anchor.X().IsAuto())
     // Shift the origin back to transform-origin.
     transform.Translate(-origin_shift_x, -origin_shift_y);
 }

third_party/WebKit/Source/core/style/ComputedStyle.h

@@ -1705,7 +1705,7 @@ class ComputedStyle : public ComputedStyleBase,
 
   // Motion utility functions.
   bool HasOffset() const {
-    return (OffsetPosition().X() != Length(kAuto)) || OffsetPath();
+    return !OffsetPosition().X().IsAuto() || OffsetPath();
   }
 
   // Direction utility functions.