Bug 1738608 - Make autofill background configurable via system color prefs. r=mstange

And remove the autofill.background pref for 95 (or 96, depending on
when this lands) assuming nothing terrible causes us to turn it off on
94.

Differential Revision: https://phabricator.services.mozilla.com/D129988

layout/style/res/forms.css

@@ -983,27 +983,9 @@ input:is([type=date], [type=time], [type=datetime-local]):is(:disabled, :read-on
 }
 
 input:autofill {
-  filter: grayscale(21%) brightness(88%) contrast(161%) invert(10%) sepia(40%) saturate(206%);
-}
-
-@supports -moz-bool-pref("layout.css.autofill.background") {
-  /* We find a few pages where using `filter` causes issues because it
-   * changes the z-order (see bug 1687682, bug 1727950).
-   *
-   * The idea behind using background-image instead of plain background-color,
-   * is that it's less likely to be overridden by the page.
-   *
-   * The color is chosen so that you get the same final color on a white
-   * background as the filter above (#fffcc8), but with some alpha so as to
-   * prevent fully illegible text.
-   *
-   * NOTE(emilio): Keep the color in sync with kAutofillColor in
-   * nsNativeBasicTheme!
-   */
-  input:autofill {
-    filter: none;
-    background-image: linear-gradient(rgba(255, 249, 145, 0.5), rgba(255, 249, 145, 0.5));
-  }
+  /* The idea behind using background-image instead of plain background-color
+   * is that it's less likely to be overridden by the page. */
+  background-image: linear-gradient(-moz-autofill-background, -moz-autofill-background);
 }
 
 input:-moz-autofill-preview {

layout/style/test/test_non_content_accessible_values.html

@@ -17,6 +17,7 @@ const NON_CONTENT_ACCESSIBLE_VALUES = {
     "text-select-background",
     "text-select-background-disabled",
     "text-select-background-attention",
+    "-moz-autofill-background",
   ],
   "display": [
     "-moz-deck",

modules/libpref/init/StaticPrefList.yaml

@@ -6824,12 +6824,6 @@
   mirror: always
   rust: true
 
-# Whether to use background-image to style autofill controls.
-- name: layout.css.autofill.background
-  type: bool
-  value: true
-  mirror: always
-
 # Whether the `:-moz-submit-invalid` pseudo-class is exposed to content.
 - name: layout.css.moz-submit-invalid.enabled
   type: RelaxedAtomicBool

modules/libpref/init/all.js

@@ -713,6 +713,19 @@ pref("ui.textHighlightBackground", "#ef0fff");
 // The foreground color for the matched text in findbar highlighting
 // Used with nsISelectionController::SELECTION_FIND
 pref("ui.textHighlightForeground", "#ffffff");
+// The background color for :autofill-ed inputs.
+//
+// In the past, we used the following `filter` to paint autofill backgrounds:
+//
+//   grayscale(21%) brightness(88%) contrast(161%) invert(10%) sepia(40%) saturate(206%);
+//
+// but there are some pages where using `filter` caused issues because it
+// changes the z-order (see bug 1687682, bug 1727950).
+//
+// The color is chosen so that you get the same final color on a white
+// background as the filter above (#fffcc8), but with some alpha so as to
+// prevent fully illegible text.
+pref("ui.-moz-autofill-background", "rgba(255, 249, 145, .5)");
 
 // We want the ability to forcibly disable platform a11y, because
 // some non-a11y-related components attempt to bring it up.  See bug

servo/components/style/values/specified/color.rs

@@ -411,6 +411,10 @@ pub enum SystemColor {
     #[parse(condition = "ParserContext::in_ua_or_chrome_sheet")]
     MozAccentColorForeground,
 
+    /// The background-color for :autofill-ed inputs.
+    #[parse(condition = "ParserContext::in_ua_or_chrome_sheet")]
+    MozAutofillBackground,
+
     /// Media rebar text.
     MozWinMediatext,
     /// Communications rebar text.

widget/nsNativeBasicTheme.cpp

@@ -488,10 +488,6 @@ std::pair<sRGBColor, sRGBColor> nsNativeBasicTheme::ComputeButtonColors(
   return std::make_pair(backgroundColor, borderColor);
 }
 
-// NOTE: This should be kept in sync with forms.css, see the comment in the
-// input:autofill rule.
-constexpr nscolor kAutofillColor = NS_RGBA(255, 249, 145, 128);
-
 std::pair<sRGBColor, sRGBColor> nsNativeBasicTheme::ComputeTextfieldColors(
     const EventStates& aState, const Colors& aColors,
     OutlineCoversBorder aOutlineCoversBorder) {
@@ -502,9 +498,10 @@ std::pair<sRGBColor, sRGBColor> nsNativeBasicTheme::ComputeTextfieldColors(
     return aColors.SystemNs(StyleSystemColor::Field);
   }();
 
-  if (aState.HasState(NS_EVENT_STATE_AUTOFILL) &&
-      StaticPrefs::layout_css_autofill_background()) {
-    backgroundColor = NS_ComposeColors(backgroundColor, kAutofillColor);
+  if (aState.HasState(NS_EVENT_STATE_AUTOFILL)) {
+    backgroundColor = NS_ComposeColors(
+        backgroundColor,
+        aColors.SystemNs(StyleSystemColor::MozAutofillBackground));
   }
 
   const sRGBColor borderColor =

widget/nsXPLookAndFeel.cpp

@@ -305,6 +305,7 @@ static const char sColorPrefs[][41] = {
     "ui.-moz-mac-tooltip",
     "ui.-moz-accent-color",
     "ui.-moz-accent-color-foreground",
+    "ui.-moz-autofill-background",
     "ui.-moz-win-mediatext",
     "ui.-moz-win-communicationstext",
     "ui.-moz-nativehyperlinktext",