style: Change StaticPrefs from a class to a namespace.

This doesn't change the way C++ code uses static prefs. But it does slightly
change how Rust code uses static prefs, specifically the name generated by
bindgen is slightly different.

The commit also improves some comments.

Differential Revision: https://phabricator.services.mozilla.com/D35764

components/style/font_face.rs

@@ -416,13 +416,13 @@ macro_rules! is_descriptor_enabled {
     ("font-display") => {
         unsafe {
             use crate::gecko_bindings::structs::mozilla;
-            mozilla::StaticPrefs_sVarCache_layout_css_font_display_enabled
+            mozilla::StaticPrefs::sVarCache_layout_css_font_display_enabled
         }
     };
     ("font-variation-settings") => {
         unsafe {
             use crate::gecko_bindings::structs::mozilla;
-            mozilla::StaticPrefs_sVarCache_layout_css_font_variations_enabled != 0
+            mozilla::StaticPrefs::sVarCache_layout_css_font_variations_enabled != 0
         }
     };
     ($name:tt) => {

components/style/gecko/media_queries.rs

@@ -271,7 +271,7 @@ impl Device {
             return true;
         }
         let document_color_use =
-            unsafe { structs::StaticPrefs_sVarCache_browser_display_document_color_use };
+            unsafe { structs::StaticPrefs::sVarCache_browser_display_document_color_use };
         let prefs = self.pref_sheet_prefs();
         match document_color_use {
             1 => true,

components/style/gecko/pseudo_element_definition.mako.rs

@@ -112,7 +112,7 @@ impl PseudoElement {
             % for pseudo in PSEUDOS:
                 ${pseudo_element_variant(pseudo)} =>
                 % if pseudo.is_tree_pseudo_element():
-                    if unsafe { structs::StaticPrefs_sVarCache_layout_css_xul_tree_pseudos_content_enabled } {
+                    if unsafe { structs::StaticPrefs::sVarCache_layout_css_xul_tree_pseudos_content_enabled } {
                         0
                     } else {
                         structs::CSS_PSEUDO_ELEMENT_ENABLED_IN_UA_SHEETS_AND_CHROME
@@ -210,7 +210,7 @@ impl PseudoElement {
                     return PseudoElement::tree_pseudo_element(name, Box::new([]))
                 }
                 if unsafe {
-                    structs::StaticPrefs_sVarCache_layout_css_unknown_webkit_pseudo_element
+                    structs::StaticPrefs::sVarCache_layout_css_unknown_webkit_pseudo_element
                 } {
                     const WEBKIT_PREFIX: &str = "-webkit-";
                     if starts_with_ignore_ascii_case(name, WEBKIT_PREFIX) {

components/style/gecko/selector_parser.rs

@@ -175,7 +175,7 @@ impl NonTSPseudoClass {
             // For pseudo-classes with pref, the availability in content
             // depends on the pref.
             NonTSPseudoClass::Fullscreen => unsafe {
-                mozilla::StaticPrefs_sVarCache_full_screen_api_unprefix_enabled
+                mozilla::StaticPrefs::sVarCache_full_screen_api_unprefix_enabled
             },
             // Otherwise, a pseudo-class is enabled in content when it
             // doesn't have any enabled flag.
@@ -355,7 +355,7 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
     #[inline]
     fn parse_part(&self) -> bool {
         self.chrome_rules_enabled() ||
-            unsafe { structs::StaticPrefs_sVarCache_layout_css_shadow_parts_enabled }
+            unsafe { structs::StaticPrefs::sVarCache_layout_css_shadow_parts_enabled }
     }
 
     fn parse_non_ts_pseudo_class(

components/style/media_queries/media_feature_expression.rs

@@ -302,7 +302,7 @@ impl MediaFeatureExpression {
                         feature_name = &feature_name[8..];
                         requirements.insert(ParsingRequirements::WEBKIT_PREFIX);
                         if unsafe {
-                            structs::StaticPrefs_sVarCache_layout_css_prefixes_device_pixel_ratio_webkit
+                            structs::StaticPrefs::sVarCache_layout_css_prefixes_device_pixel_ratio_webkit
                         } {
                             requirements.insert(
                                 ParsingRequirements::WEBKIT_DEVICE_PIXEL_RATIO_PREF_ENABLED,

components/style/properties/cascade.rs

@@ -686,7 +686,7 @@ impl<'a, 'b: 'a> Cascade<'a, 'b> {
             return;
         }
 
-        let use_document_fonts = unsafe { structs::StaticPrefs_sVarCache_browser_display_use_document_fonts != 0 };
+        let use_document_fonts = unsafe { structs::StaticPrefs::sVarCache_browser_display_use_document_fonts != 0 };
         let builder = &mut self.context.builder;
         let (default_font_type, prioritize_user_fonts) = {
             let font = builder.get_font().gecko();

components/style/stylesheets/document_rule.rs

@@ -260,12 +260,12 @@ impl DocumentCondition {
             return true;
         }
 
-        if unsafe { structs::StaticPrefs_sVarCache_layout_css_moz_document_content_enabled } {
+        if unsafe { structs::StaticPrefs::sVarCache_layout_css_moz_document_content_enabled } {
             return true;
         }
 
         if !unsafe {
-            structs::StaticPrefs_sVarCache_layout_css_moz_document_url_prefix_hack_enabled
+            structs::StaticPrefs::sVarCache_layout_css_moz_document_url_prefix_hack_enabled
         } {
             return false;
         }

components/style/stylesheets/supports_rule.rs

@@ -324,7 +324,7 @@ impl RawSelector {
         #[cfg(feature = "gecko")]
         {
             if unsafe {
-                !crate::gecko_bindings::structs::StaticPrefs_sVarCache_layout_css_supports_selector_enabled
+                !crate::gecko_bindings::structs::StaticPrefs::sVarCache_layout_css_supports_selector_enabled
             } {
                 return false;
             }

components/style/values/generics/easing.rs

@@ -70,7 +70,7 @@ pub enum TimingKeyword {
 #[cfg(feature = "gecko")]
 fn step_position_jump_enabled(_context: &ParserContext) -> bool {
     use crate::gecko_bindings::structs;
-    unsafe { structs::StaticPrefs_sVarCache_layout_css_step_position_jump_enabled }
+    unsafe { structs::StaticPrefs::sVarCache_layout_css_step_position_jump_enabled }
 }
 
 #[cfg(feature = "servo")]

components/style/values/generics/text.rs

@@ -75,7 +75,7 @@ fn line_height_moz_block_height_enabled(context: &ParserContext) -> bool {
     use crate::gecko_bindings::structs;
     context.in_ua_sheet() ||
         unsafe {
-            structs::StaticPrefs_sVarCache_layout_css_line_height_moz_block_height_content_enabled
+            structs::StaticPrefs::sVarCache_layout_css_line_height_moz_block_height_content_enabled
         }
 }
 

components/style/values/specified/basic_shape.rs

@@ -60,7 +60,7 @@ pub type Polygon = generic::GenericPolygon<LengthPercentage>;
 fn is_clip_path_path_enabled(context: &ParserContext) -> bool {
     use crate::gecko_bindings::structs::mozilla;
     context.chrome_rules_enabled() ||
-        unsafe { mozilla::StaticPrefs_sVarCache_layout_css_clip_path_path_enabled }
+        unsafe { mozilla::StaticPrefs::sVarCache_layout_css_clip_path_path_enabled }
 }
 #[cfg(feature = "servo")]
 fn is_clip_path_path_enabled(_: &ParserContext) -> bool {

components/style/values/specified/box.rs

@@ -25,15 +25,15 @@ use style_traits::{SpecifiedValueInfo, StyleParseErrorKind, ToCss};
 fn moz_display_values_enabled(context: &ParserContext) -> bool {
     use crate::gecko_bindings::structs;
     context.in_ua_or_chrome_sheet() ||
-        unsafe { structs::StaticPrefs_sVarCache_layout_css_xul_display_values_content_enabled }
+        unsafe { structs::StaticPrefs::sVarCache_layout_css_xul_display_values_content_enabled }
 }
 
 #[cfg(feature = "gecko")]
 fn moz_box_display_values_enabled(context: &ParserContext) -> bool {
     use crate::gecko_bindings::structs;
     context.in_ua_or_chrome_sheet() ||
         unsafe {
-            structs::StaticPrefs_sVarCache_layout_css_xul_box_display_values_content_enabled
+            structs::StaticPrefs::sVarCache_layout_css_xul_box_display_values_content_enabled
         }
 }
 

components/style/values/specified/grid.rs

@@ -381,7 +381,7 @@ impl ToComputedValue for TrackList<LengthPercentage, Integer> {
 #[inline]
 fn allow_grid_template_subgrids() -> bool {
     use crate::gecko_bindings::structs::mozilla;
-    unsafe { mozilla::StaticPrefs_sVarCache_layout_css_grid_template_subgrid_value_enabled }
+    unsafe { mozilla::StaticPrefs::sVarCache_layout_css_grid_template_subgrid_value_enabled }
 }
 
 #[cfg(feature = "servo")]

components/style/values/specified/svg.rs

@@ -36,7 +36,7 @@ pub type SVGStrokeDashArray = generic::SVGStrokeDashArray<NonNegativeLengthPerce
 #[cfg(feature = "gecko")]
 pub fn is_context_value_enabled() -> bool {
     use crate::gecko_bindings::structs::mozilla;
-    unsafe { mozilla::StaticPrefs_sVarCache_gfx_font_rendering_opentype_svg_enabled }
+    unsafe { mozilla::StaticPrefs::sVarCache_gfx_font_rendering_opentype_svg_enabled }
 }
 
 /// Whether the `context-value` value is enabled.