Issue #1689 - Part 3: Add a preference for animation composite modes.

This feature should not be shipped until the various definitions of addition for
each additive property are properly specified and then implemented accordingly.

Unlike other patches in this series, compositing is not frequently used
internally so there is no need to enable this by default for chrome callers.

4 files changed, 8 insertions, 5 deletions

diff --git a/dom/animation/KeyframeEffect.cpp b/dom/animation/KeyframeEffect.cpp
index 90230a5b4..090c7019d 100644
--- a/dom/animation/KeyframeEffect.cpp
+++ b/dom/animation/KeyframeEffect.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/dom/AnimationEffectTiming.h"
 #include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/KeyframeUtils.h"
+#include "mozilla/Preferences.h"
 #include "nsContentUtils.h"
 #include "nsDOMMutationObserver.h" // For nsAutoAnimationMutationBatch
 #include "nsIScriptError.h"
@@ -135,9 +136,9 @@ void
 KeyframeEffect::SetIterationComposite(
   const IterationCompositeOperation& aIterationComposite)
 {
-  // Ignore iterationComposite if the Web Animations API is not enabled,
+  // Ignore iterationComposite if the API is not enabled,
   // then the default value 'Replace' will be used.
-  if (!AnimationUtils::IsCoreAPIEnabledForCaller()) {
+  if (!Preferences::GetBool("dom.animations-api.compositing.enabled")) {
     return;
   }
 
diff --git a/dom/animation/test/mochitest.ini b/dom/animation/test/mochitest.ini
index b56136d25..fff62ac7c 100644
--- a/dom/animation/test/mochitest.ini
+++ b/dom/animation/test/mochitest.ini
@@ -1,5 +1,6 @@
 [DEFAULT]
 prefs =
+  dom.animations-api.compositing.enabled=true
   dom.animations-api.core.enabled=true
   dom.animations-api.implicit-keyframes.enabled=true
   dom.animations-api.timelines.enabled=true
diff --git a/layout/reftests/web-animations/reftest.list b/layout/reftests/web-animations/reftest.list
index eefd41f49..da1d07089 100644
--- a/layout/reftests/web-animations/reftest.list
+++ b/layout/reftests/web-animations/reftest.list
@@ -15,6 +15,6 @@ test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-ch
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-effect.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-display-property.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-losing-css-animation-in-delay.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-accumulate-to-replace.html style-updates-for-iteration-composite-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-replace-to-accumulate.html style-updates-for-iteration-composite-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-current-iteration-changed.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-iteration-composition-changed-from-accumulate-to-replace.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-iteration-composition-changed-from-replace-to-accumulate.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-current-iteration-changed.html style-updates-for-iteration-composite-ref.html
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index a4ebdde3e..3319045e7 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2720,6 +2720,7 @@ pref("dom.animations-api.core.enabled", true);
 #endif
 pref("dom.animations-api.timelines.enabled", false);
 pref("dom.animations-api.implicit-keyframes.enabled", false);
+pref("dom.animations-api.compositing.enabled", false);
 
 // Is support for the Element.animate() function (a subset of the Web Animations
 // API) enabled?