diff --git a/dom/animation/ComputedTiming.h b/dom/animation/ComputedTiming.h
new file mode 100644
index 000000000000..13b902f0d485
--- /dev/null
+++ b/dom/animation/ComputedTiming.h
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ComputedTiming_h
+#define mozilla_ComputedTiming_h
+
+#include "mozilla/dom/Nullable.h"
+#include "mozilla/StickyTimeDuration.h"
+
+// X11 has a #define for None
+#ifdef None
+#undef None
+#endif
+#include "mozilla/dom/AnimationEffectReadOnlyBinding.h" // FillMode
+
+namespace mozilla {
+
+/**
+ * Stores the results of calculating the timing properties of an animation
+ * at a given sample time.
+ */
+struct ComputedTiming
+{
+  // The total duration of the animation including all iterations.
+  // Will equal StickyTimeDuration::Forever() if the animation repeats
+  // indefinitely.
+  StickyTimeDuration  mActiveDuration;
+  // The effect end time in local time (i.e. an offset from the effect's
+  // start time). Will equal StickyTimeDuration::Forever() if the animation
+  // plays indefinitely.
+  StickyTimeDuration  mEndTime;
+  // Progress towards the end of the current iteration. If the effect is
+  // being sampled backwards, this will go from 1.0 to 0.0.
+  // Will be null if the animation is neither animating nor
+  // filling at the sampled time.
+  Nullable<double>    mProgress;
+  // Zero-based iteration index (meaningless if mProgress is null).
+  uint64_t            mCurrentIteration = 0;
+  // Unlike TimingParams::mIterations, this value is
+  // guaranteed to be in the range [0, Infinity].
+  double              mIterations = 1.0;
+  double              mIterationStart = 0.0;
+  StickyTimeDuration  mDuration;
+
+  // This is the computed fill mode so it is never auto
+  dom::FillMode       mFill = dom::FillMode::None;
+  bool FillsForwards() const {
+    MOZ_ASSERT(mFill != dom::FillMode::Auto,
+               "mFill should not be Auto in ComputedTiming.");
+    return mFill == dom::FillMode::Both ||
+           mFill == dom::FillMode::Forwards;
+  }
+  bool FillsBackwards() const {
+    MOZ_ASSERT(mFill != dom::FillMode::Auto,
+               "mFill should not be Auto in ComputedTiming.");
+    return mFill == dom::FillMode::Both ||
+           mFill == dom::FillMode::Backwards;
+  }
+
+  enum class AnimationPhase {
+    Null,   // Not sampled (null sample time)
+    Before, // Sampled prior to the start of the active interval
+    Active, // Sampled within the active interval
+    After   // Sampled after (or at) the end of the active interval
+  };
+  AnimationPhase      mPhase = AnimationPhase::Null;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ComputedTiming_h
diff --git a/dom/animation/KeyframeEffect.h b/dom/animation/KeyframeEffect.h
index 172f58d5df05..da4468d40341 100644
--- a/dom/animation/KeyframeEffect.h
+++ b/dom/animation/KeyframeEffect.h
@@ -13,10 +13,11 @@
 #include "nsWrapperCache.h"
 #include "mozilla/AnimationPerformanceWarning.h"
 #include "mozilla/Attributes.h"
-#include "mozilla/ComputedTimingFunction.h" // ComputedTimingFunction
-#include "mozilla/LayerAnimationInfo.h"     // LayerAnimations::kRecords
+#include "mozilla/ComputedTiming.h"
+#include "mozilla/ComputedTimingFunction.h"
+#include "mozilla/LayerAnimationInfo.h" // LayerAnimations::kRecords
 #include "mozilla/NonOwningAnimationTarget.h"
-#include "mozilla/OwningNonNull.h"          // OwningNonNull<...>
+#include "mozilla/OwningNonNull.h"      // OwningNonNull<...>
 #include "mozilla/StickyTimeDuration.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/TimeStamp.h"
@@ -50,57 +51,6 @@ enum class CompositeOperation : uint32_t;
 struct AnimationPropertyDetails;
 }
 
-/**
- * Stores the results of calculating the timing properties of an animation
- * at a given sample time.
- */
-struct ComputedTiming
-{
-  // The total duration of the animation including all iterations.
-  // Will equal StickyTimeDuration::Forever() if the animation repeats
-  // indefinitely.
-  StickyTimeDuration  mActiveDuration;
-  // The effect end time in local time (i.e. an offset from the effect's
-  // start time). Will equal StickyTimeDuration::Forever() if the animation
-  // plays indefinitely.
-  StickyTimeDuration  mEndTime;
-  // Progress towards the end of the current iteration. If the effect is
-  // being sampled backwards, this will go from 1.0 to 0.0.
-  // Will be null if the animation is neither animating nor
-  // filling at the sampled time.
-  Nullable<double>    mProgress;
-  // Zero-based iteration index (meaningless if mProgress is null).
-  uint64_t            mCurrentIteration = 0;
-  // Unlike TimingParams::mIterations, this value is
-  // guaranteed to be in the range [0, Infinity].
-  double              mIterations = 1.0;
-  double              mIterationStart = 0.0;
-  StickyTimeDuration  mDuration;
-
-  // This is the computed fill mode so it is never auto
-  dom::FillMode       mFill = dom::FillMode::None;
-  bool FillsForwards() const {
-    MOZ_ASSERT(mFill != dom::FillMode::Auto,
-               "mFill should not be Auto in ComputedTiming.");
-    return mFill == dom::FillMode::Both ||
-           mFill == dom::FillMode::Forwards;
-  }
-  bool FillsBackwards() const {
-    MOZ_ASSERT(mFill != dom::FillMode::Auto,
-               "mFill should not be Auto in ComputedTiming.");
-    return mFill == dom::FillMode::Both ||
-           mFill == dom::FillMode::Backwards;
-  }
-
-  enum class AnimationPhase {
-    Null,   // Not sampled (null sample time)
-    Before, // Sampled prior to the start of the active interval
-    Active, // Sampled within the active interval
-    After   // Sampled after (or at) the end of the active interval
-  };
-  AnimationPhase      mPhase = AnimationPhase::Null;
-};
-
 struct AnimationPropertySegment
 {
   float mFromKey, mToKey;
diff --git a/dom/animation/moz.build b/dom/animation/moz.build
index 8dcb1c1ad01f..7ec054c06037 100644
--- a/dom/animation/moz.build
+++ b/dom/animation/moz.build
@@ -23,6 +23,7 @@ EXPORTS.mozilla += [
     'AnimationPerformanceWarning.h',
     'AnimationUtils.h',
     'AnimValuesStyleRule.h',
+    'ComputedTiming.h',
     'ComputedTimingFunction.h',
     'EffectCompositor.h',
     'EffectSet.h',