Issue #1705 - Part 4: Add scrollbar-width CSS keyword to CSS parser.

This should be all parts needed to add a brand new enum keyword including
getting the computed style from it...

devtools/shared/css/generated/properties-db.js

@@ -3038,6 +3038,7 @@ exports.CSS_PROPERTIES = {
       "scroll-snap-points-y",
       "scroll-snap-type-x",
       "scroll-snap-type-y",
+      "scrollbar-width",
       "shape-outside",
       "shape-rendering",
       "-moz-stack-sizing",

layout/style/nsCSSKeywordList.h

@@ -509,6 +509,7 @@ CSS_KEY(scrollbar, scrollbar)
 CSS_KEY(scrollbar-small, scrollbar_small)
 CSS_KEY(scrollbar-horizontal, scrollbar_horizontal)
 CSS_KEY(scrollbar-vertical, scrollbar_vertical)
+CSS_KEY(scrollbar-width, scrollbar_width)
 CSS_KEY(se-resize, se_resize)
 CSS_KEY(select-after, select_after)
 CSS_KEY(select-all, select_all)

layout/style/nsCSSPropList.h

@@ -3709,6 +3709,16 @@ CSS_PROP_DISPLAY(
     kScrollSnapTypeKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
+CSS_PROP_USERINTERFACE(
+    scrollbar-width,
+    scrollbar_width,
+    ScrollbarWidth,
+    CSS_PROPERTY_PARSE_VALUE,
+    "layout.css.scrollbar-width.enabled",
+    VARIANT_HK,
+    kScrollbarWidthKTable,
+    CSS_PROP_NO_OFFSET,
+    eStyleAnimType_Discrete)
 CSS_PROP_DISPLAY(
     shape-outside,
     shape_outside,

layout/style/nsCSSProps.cpp

@@ -2009,6 +2009,12 @@ const KTableEntry nsCSSProps::kScrollSnapTypeKTable[] = {
   { eCSSKeyword_UNKNOWN,   -1 }
 };
 
+const KTableEntry nsCSSProps::kScrollbarWidthKTable[] = {
+  { eCSSKeyword_auto, StyleScrollbarWidth::Auto },
+  { eCSSKeyword_thin, StyleScrollbarWidth::Thin },
+  { eCSSKeyword_none, StyleScrollbarWidth::None }
+};
+
 const KTableEntry nsCSSProps::kStackSizingKTable[] = {
   { eCSSKeyword_ignore, NS_STYLE_STACK_SIZING_IGNORE },
   { eCSSKeyword_stretch_to_fit, NS_STYLE_STACK_SIZING_STRETCH_TO_FIT },

layout/style/nsCSSProps.h

@@ -856,6 +856,7 @@ public:
   static const KTableEntry kRubyPositionKTable[];
   static const KTableEntry kScrollBehaviorKTable[];
   static const KTableEntry kScrollSnapTypeKTable[];
+  static const KTableEntry kScrollbarWidthKTable[];
   static const KTableEntry kSpeakKTable[];
   static const KTableEntry kSpeakHeaderKTable[];
   static const KTableEntry kSpeakNumeralKTable[];

layout/style/nsComputedDOMStyle.cpp

@@ -3305,6 +3305,16 @@ nsComputedDOMStyle::DoGetScrollSnapTypeY()
   return val.forget();
 }
 
+already_AddRefed<CSSValue>
+nsComputedDOMStyle::DoGetScrollbarWidth()
+{
+  RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
+  val->SetIdent(
+    nsCSSProps::ValueToKeywordEnum(StyleUserInterface()->mScrollbarWidth,
+                                   nsCSSProps::kScrollbarWidthKTable));
+  return val.forget();
+}
+
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::GetScrollSnapPoints(const nsStyleCoord& aCoord)
 {

layout/style/nsComputedDOMStyle.h

@@ -492,6 +492,7 @@ private:
   already_AddRefed<CSSValue> DoGetCursor();
   already_AddRefed<CSSValue> DoGetForceBrokenImageIcon();
   already_AddRefed<CSSValue> DoGetIMEMode();
+  already_AddRefed<CSSValue> DoGetScrollbarWidth();
   already_AddRefed<CSSValue> DoGetUserFocus();
   already_AddRefed<CSSValue> DoGetUserInput();
   already_AddRefed<CSSValue> DoGetUserModify();

layout/style/nsComputedDOMStylePropertyList.h

@@ -226,6 +226,7 @@ COMPUTED_STYLE_PROP(scroll_snap_points_x,          ScrollSnapPointsX)
 COMPUTED_STYLE_PROP(scroll_snap_points_y,          ScrollSnapPointsY)
 COMPUTED_STYLE_PROP(scroll_snap_type_x,            ScrollSnapTypeX)
 COMPUTED_STYLE_PROP(scroll_snap_type_y,            ScrollSnapTypeY)
+COMPUTED_STYLE_PROP(scrollbar_width,               ScrollbarWidth)
 COMPUTED_STYLE_PROP(shape_outside,                 ShapeOutside)
 //// COMPUTED_STYLE_PROP(size,                     Size)
 COMPUTED_STYLE_PROP(tab_size,			   TabSize)

layout/style/nsRuleNode.cpp

@@ -1394,6 +1394,7 @@ struct SetEnumValueHelper
   DEFINE_ENUM_CLASS_SETTER(StyleFillRule, Nonzero, Evenodd)
   DEFINE_ENUM_CLASS_SETTER(StyleFloat, None, InlineEnd)
   DEFINE_ENUM_CLASS_SETTER(StyleFloatEdge, ContentBox, MarginBox)
+  DEFINE_ENUM_CLASS_SETTER(StyleScrollbarWidth, Auto, None)
   DEFINE_ENUM_CLASS_SETTER(StyleTextJustify, None, InterCharacter)
   DEFINE_ENUM_CLASS_SETTER(StyleUserFocus, None, SelectMenu)
   DEFINE_ENUM_CLASS_SETTER(StyleUserSelect, None, MozText)
@@ -5236,6 +5237,14 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
   setComplexColor(aRuleData->ValueForCaretColor(),
                   &nsStyleUserInterface::mCaretColor);
   
+  // scrollbar-width: auto, thin, none
+  SetValue(*aRuleData->ValueForScrollbarWidth(),
+           ui->mScrollbarWidth,
+           conditions,
+           SETVAL_ENUMERATED,
+           parentUI->mScrollbarWidth,
+           StyleScrollbarWidth::Auto);
+
   COMPUTE_END_INHERITED(UserInterface, ui)
 }
 

layout/style/nsStyleConsts.h

@@ -187,6 +187,13 @@ enum class StyleFloatEdge : uint8_t {
   MarginBox,
 };
 
+// scrollbar-width
+enum class StyleScrollbarWidth : uint8_t {
+  Auto,
+  Thin,
+  None,
+};
+
 // shape-box for shape-outside
 enum class StyleShapeOutsideShapeBox : uint8_t {
   NoBox,

layout/style/nsStyleStruct.cpp

@@ -4024,6 +4024,7 @@ nsStyleUserInterface::nsStyleUserInterface(StyleStructContext aContext)
   , mPointerEvents(NS_STYLE_POINTER_EVENTS_AUTO)
   , mCursor(NS_STYLE_CURSOR_AUTO)
   , mCaretColor(StyleComplexColor::Auto())
+  , mScrollbarWidth(StyleScrollbarWidth::Auto)
 {
   MOZ_COUNT_CTOR(nsStyleUserInterface);
 }
@@ -4036,6 +4037,7 @@ nsStyleUserInterface::nsStyleUserInterface(const nsStyleUserInterface& aSource)
   , mCursor(aSource.mCursor)
   , mCursorImages(aSource.mCursorImages)
   , mCaretColor(aSource.mCaretColor)
+  , mScrollbarWidth(aSource.mScrollbarWidth)
 {
   MOZ_COUNT_CTOR(nsStyleUserInterface);
 }
@@ -4088,6 +4090,13 @@ nsStyleUserInterface::CalcDifference(const nsStyleUserInterface& aNewData) const
     hint |= nsChangeHint_RepaintFrame;
   }
   
+  if (mScrollbarWidth != aNewData.mScrollbarWidth) {
+    // For scrollbar-width change, we need some special handling similar
+    // to overflow properties. Specifically, we may need to reconstruct
+    // the scrollbar or force reflow of the viewport scrollbar.
+    hint |= nsChangeHint_ScrollbarChange;
+  }
+
   return hint;
 }
 

layout/style/nsStyleStruct.h

@@ -3417,6 +3417,7 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleUserInterface
   uint8_t mCursor;                            // [inherited] See nsStyleConsts.h
   nsTArray<nsCursorImage> mCursorImages;      // [inherited] images and coords
   mozilla::StyleComplexColor mCaretColor;     // [inherited]
+  mozilla::StyleScrollbarWidth mScrollbarWidth;
 
   inline uint8_t GetEffectivePointerEvents(nsIFrame* aFrame) const;
 };

layout/style/test/property_database.js

@@ -7944,6 +7944,18 @@ for (var prop in gCSSProperties) {
   }
 }
 
+if (IsCSSPropertyPrefEnabled("layout.css.scrollbar-width.enabled")) {
+  gCSSProperties["scrollbar-width"] = {
+    domProp: "scrollbarWidth",
+    inherited: false,
+    type: CSS_TYPE_LONGHAND,
+    initial_values: [ "auto" ],
+    other_values: [ "none", "thin" ],
+    invalid_values: [ "1px" ]
+  };
+}
+
+
 if (false) {
   // TODO These properties are chrome-only, and are not exposed via CSSOM.
   // We may still want to find a way to test them. See bug 1206999.

modules/libpref/init/all.js

@@ -2483,6 +2483,9 @@ pref("layout.css.isolation.enabled", true);
 // Is support for CSS Filters enabled?
 pref("layout.css.filters.enabled", true);
 
+// Is support for scrollbar-width property enabled?
+pref("layout.css.scrollbar-width.enabled", false);
+
 // Set the threshold distance in CSS pixels below which scrolling will snap to
 // an edge, when scroll snapping is set to "proximity".
 pref("layout.css.scroll-snap.proximity-threshold", 200);