--- a/gfx/thebes/gfxBlur.cpp
+++ b/gfx/thebes/gfxBlur.cpp
@@ -7,16 +7,17 @@
 
 #include "gfx2DGlue.h"
 #include "gfxContext.h"
 #include "gfxPlatform.h"
 #include "mozilla/gfx/2D.h"
 #include "mozilla/gfx/Blur.h"
 #include "mozilla/gfx/PathHelpers.h"
 #include "mozilla/Maybe.h"
+#include "mozilla/SystemGroup.h"
 #include "nsExpirationTracker.h"
 #include "nsClassHashtable.h"
 #include "gfxUtils.h"
 
 using namespace mozilla;
 using namespace mozilla::gfx;
 
 gfxAlphaBoxBlur::gfxAlphaBoxBlur()
@@ -346,17 +347,18 @@ struct BlurCacheData {
  * SourceSurfaces used to draw the blurs.
  *
  * An entry stays in the cache as long as it is used often.
  */
 class BlurCache final : public nsExpirationTracker<BlurCacheData,4>
 {
   public:
     BlurCache()
-      : nsExpirationTracker<BlurCacheData, 4>(GENERATION_MS, "BlurCache")
+      : nsExpirationTracker<BlurCacheData, 4>(GENERATION_MS, "BlurCache",
+                                              SystemGroup::EventTargetFor(TaskCategory::Other))
     {
     }
 
     virtual void NotifyExpired(BlurCacheData* aObject)
     {
       RemoveObject(aObject);
       mHashEntries.Remove(aObject->mKey);
     }

--- a/gfx/thebes/gfxGradientCache.cpp
+++ b/gfx/thebes/gfxGradientCache.cpp
@@ -3,16 +3,17 @@
  * 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/. */
 
 #include "mozilla/gfx/2D.h"
 #include "nsTArray.h"
 #include "PLDHashTable.h"
 #include "nsExpirationTracker.h"
 #include "nsClassHashtable.h"
+#include "mozilla/SystemGroup.h"
 #include "mozilla/Telemetry.h"
 #include "gfxGradientCache.h"
 #include <time.h>
 
 namespace mozilla {
 namespace gfx {
 
 using namespace mozilla;
@@ -118,17 +119,18 @@ struct GradientCacheData {
  * entry is in the cache, all the references it has are guaranteed to be valid:
  * the nsStyleRect for the key, the gfxPattern for the value.
  */
 class GradientCache final : public nsExpirationTracker<GradientCacheData,4>
 {
   public:
     GradientCache()
       : nsExpirationTracker<GradientCacheData,4>(MAX_GENERATION_MS,
-                                                 "GradientCache")
+                                                 "GradientCache",
+                                                 SystemGroup::EventTargetFor(TaskCategory::Other))
     {
       srand(time(nullptr));
       mTimerPeriod = rand() % MAX_GENERATION_MS + 1;
       Telemetry::Accumulate(Telemetry::GRADIENT_RETENTION_TIME, mTimerPeriod);
     }
 
     virtual void NotifyExpired(GradientCacheData* aObject)
     {