Bug 1573268 - Convert layout.animated-image-layers.enabled to static pref. r=njn

Converts layout.animated-image-layers.enabled to a static pref and removes the nsLayoutUtils::AnimatedImageLayersEnabled() function, replacing it with the static pref.

Differential Revision: https://phabricator.services.mozilla.com/D41652

--HG--
extra : moz-landing-system : lando

layout/base/nsLayoutUtils.cpp

@@ -557,19 +557,6 @@ bool nsLayoutUtils::GPUImageScalingEnabled() {
   return sGPUImageScalingEnabled;
 }
 
-bool nsLayoutUtils::AnimatedImageLayersEnabled() {
-  static bool sAnimatedImageLayersEnabled;
-  static bool sAnimatedImageLayersPrefCached = false;
-
-  if (!sAnimatedImageLayersPrefCached) {
-    sAnimatedImageLayersPrefCached = true;
-    Preferences::AddBoolVarCache(&sAnimatedImageLayersEnabled,
-                                 "layout.animated-image-layers.enabled", false);
-  }
-
-  return sAnimatedImageLayersEnabled;
-}
-
 bool nsLayoutUtils::IsInterCharacterRubyEnabled() {
   static bool sInterCharacterRubyEnabled;
   static bool sInterCharacterRubyEnabledPrefCached = false;

layout/base/nsLayoutUtils.h

@@ -2397,11 +2397,6 @@ class nsLayoutUtils {
    */
   static bool GPUImageScalingEnabled();
 
-  /**
-   * Checks whether we want to layerize animated images whenever possible.
-   */
-  static bool AnimatedImageLayersEnabled();
-
   /**
    * Checks whether support for inter-character ruby is enabled.
    */

layout/generic/nsImageFrame.cpp

@@ -29,6 +29,7 @@
 #include "mozilla/MouseEvents.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/PresShellInlines.h"
+#include "mozilla/StaticPrefs_layout.h"
 #include "mozilla/Unused.h"
 
 #include "nsCOMPtr.h"
@@ -1777,7 +1778,7 @@ LayerState nsDisplayImage::GetLayerState(
     const ContainerLayerParameters& aParameters) {
   if (!nsDisplayItem::ForceActiveLayers()) {
     bool animated = false;
-    if (!nsLayoutUtils::AnimatedImageLayersEnabled() ||
+    if (!StaticPrefs::layout_animated_image_layers_enabled() ||
         mImage->GetType() != imgIContainer::TYPE_RASTER ||
         NS_FAILED(mImage->GetAnimated(&animated)) || !animated) {
       if (!aManager->IsCompositingCheap() ||

layout/painting/nsDisplayList.cpp

@@ -4456,7 +4456,7 @@ nsDisplayBackgroundImage::ShouldCreateOwnLayer(nsDisplayListBuilder* aBuilder,
     return WHENEVER_POSSIBLE;
   }
 
-  if (nsLayoutUtils::AnimatedImageLayersEnabled() && mBackgroundStyle) {
+  if (StaticPrefs::layout_animated_image_layers_enabled() && mBackgroundStyle) {
     const nsStyleImageLayers::Layer& layer =
         mBackgroundStyle->StyleBackground()->mImage.mLayers[mLayer];
     const nsStyleImage* image = &layer.mImage;

modules/libpref/init/StaticPrefList.yaml

@@ -4027,6 +4027,12 @@
   value: false
   mirror: always
 
+# Whether we should layerize all animated images (if otherwise possible).
+- name: layout.animated-image-layers.enabled
+  type: bool
+  value: false
+  mirror: always
+
 - name: layout.animation.prerender.partial
   type: RelaxedAtomicBool
   value: false

modules/libpref/init/all.js

@@ -4950,9 +4950,6 @@ pref("full-screen-api.warning.delay", 500);
 // time for the warning box stays on the screen before sliding out, unit: ms
 pref("pointer-lock-api.warning.timeout", 3000);
 
-// Whether we should layerize all animated images (if otherwise possible).
-pref("layout.animated-image-layers.enabled", false);
-
 pref("dom.vibrator.enabled", true);
 pref("dom.vibrator.max_vibrate_ms", 10000);
 pref("dom.vibrator.max_vibrate_list_len", 128);