--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -143,29 +143,16 @@ NS_IMPL_ISUPPORTS(ContentListener, nsIDO
 
 static const CSSSize kDefaultViewportSize(980, 480);
 
 static const char BEFORE_FIRST_PAINT[] = "before-first-paint";
 
 typedef nsDataHashtable<nsUint64HashKey, TabChild*> TabChildMap;
 static TabChildMap* sTabChildren;
 
-static bool
-UsingCompositorLRU()
-{
-  static bool sHavePrefs = false;
-  static uint32_t sCompositorLRUSize = 0;
-  if (!sHavePrefs) {
-    sHavePrefs = true;
-    Preferences::AddUintVarCache(&sCompositorLRUSize,
-                                 "layers.compositor-lru-size", 0);
-  }
-  return sCompositorLRUSize != 0;
-}
-
 TabChildBase::TabChildBase()
   : mTabChildGlobal(nullptr)
 {
   mozilla::HoldJSObjects(this);
 }
 
 TabChildBase::~TabChildBase()
 {
@@ -2867,38 +2854,29 @@ TabChild::NotifyPainted()
         mRemoteFrame->SendNotifyCompositorTransaction();
         mNotified = true;
     }
 }
 
 void
 TabChild::MakeVisible()
 {
-  CompositorBridgeChild* compositor = CompositorBridgeChild::Get();
-  if (UsingCompositorLRU()) {
-    compositor->SendNotifyVisible(mLayersId);
-  }
-
   if (mPuppetWidget) {
     mPuppetWidget->Show(true);
   }
 }
 
 void
 TabChild::MakeHidden()
 {
   CompositorBridgeChild* compositor = CompositorBridgeChild::Get();
-  if (UsingCompositorLRU()) {
-    compositor->SendNotifyHidden(mLayersId);
-  } else {
-    // Clear cached resources directly. This avoids one extra IPC
-    // round-trip from CompositorBridgeChild to CompositorBridgeParent when
-    // CompositorLRU is not used.
-    compositor->RecvClearCachedResources(mLayersId);
-  }
+
+  // Clear cached resources directly. This avoids one extra IPC
+  // round-trip from CompositorBridgeChild to CompositorBridgeParent.
+  compositor->RecvClearCachedResources(mLayersId);
 
   if (mPuppetWidget) {
     mPuppetWidget->Show(false);
   }
 }
 
 void
 TabChild::UpdateHitRegion(const nsRegion& aRegion)

--- a/gfx/layers/ipc/CompositorBridgeChild.cpp
+++ b/gfx/layers/ipc/CompositorBridgeChild.cpp
@@ -694,36 +694,16 @@ CompositorBridgeChild::SendResume()
   MOZ_ASSERT(mCanSend);
   if (!mCanSend) {
     return true;
   }
   return PCompositorBridgeChild::SendResume();
 }
 
 bool
-CompositorBridgeChild::SendNotifyHidden(const uint64_t& id)
-{
-  MOZ_ASSERT(mCanSend);
-  if (!mCanSend) {
-    return true;
-  }
-  return PCompositorBridgeChild::SendNotifyHidden(id);
-}
-
-bool
-CompositorBridgeChild::SendNotifyVisible(const uint64_t& id)
-{
-  MOZ_ASSERT(mCanSend);
-  if (!mCanSend) {
-    return true;
-  }
-  return PCompositorBridgeChild::SendNotifyVisible(id);
-}
-
-bool
 CompositorBridgeChild::SendNotifyChildCreated(const uint64_t& id)
 {
   MOZ_ASSERT(mCanSend);
   if (!mCanSend) {
     return true;
   }
   return PCompositorBridgeChild::SendNotifyChildCreated(id);
 }

--- a/gfx/layers/ipc/CompositorBridgeChild.h
+++ b/gfx/layers/ipc/CompositorBridgeChild.h
@@ -144,18 +144,16 @@ public:
   // are not virtual), they just overload them.
   // All of these Send* methods just add a sanity check (that it is not too late
   // send a message) and forward the call to the super-class's equivalent method.
   // This means that it is correct to call directly the super-class methods, but
   // you won't get the extra safety provided here.
   bool SendWillClose();
   bool SendPause();
   bool SendResume();
-  bool SendNotifyHidden(const uint64_t& id);
-  bool SendNotifyVisible(const uint64_t& id);
   bool SendNotifyChildCreated(const uint64_t& id);
   bool SendAdoptChild(const uint64_t& id);
   bool SendMakeSnapshot(const SurfaceDescriptor& inSnapshot, const gfx::IntRect& dirtyRect);
   bool SendFlushRendering();
   bool SendGetTileSize(int32_t* tileWidth, int32_t* tileHeight);
   bool SendStartFrameTimeRecording(const int32_t& bufferSize, uint32_t* startIndex);
   bool SendStopFrameTimeRecording(const uint32_t& startIndex, nsTArray<float>* intervals);
   bool SendNotifyRegionInvalidated(const nsIntRegion& region);

--- a/gfx/layers/ipc/CompositorBridgeParent.cpp
+++ b/gfx/layers/ipc/CompositorBridgeParent.cpp
@@ -31,17 +31,16 @@
 #include "mozilla/gfx/Rect.h"          // for IntSize
 #include "VRManager.h"                  // for VRManager
 #include "mozilla/ipc/Transport.h"      // for Transport
 #include "mozilla/layers/APZCTreeManager.h"  // for APZCTreeManager
 #include "mozilla/layers/APZThreadUtils.h"  // for APZCTreeManager
 #include "mozilla/layers/AsyncCompositionManager.h"
 #include "mozilla/layers/BasicCompositor.h"  // for BasicCompositor
 #include "mozilla/layers/Compositor.h"  // for Compositor
-#include "mozilla/layers/CompositorLRU.h"  // for CompositorLRU
 #include "mozilla/layers/CompositorOGL.h"  // for CompositorOGL
 #include "mozilla/layers/CompositorThread.h"
 #include "mozilla/layers/CompositorTypes.h"
 #include "mozilla/layers/FrameUniformityData.h"
 #include "mozilla/layers/ImageBridgeParent.h"
 #include "mozilla/layers/LayerManagerComposite.h"
 #include "mozilla/layers/LayersTypes.h"
 #include "mozilla/layers/PLayerTransactionParent.h"
@@ -1987,18 +1986,16 @@ public:
   virtual void ActorDestroy(ActorDestroyReason aWhy) override;
 
   // FIXME/bug 774388: work out what shutdown protocol we need.
   virtual bool RecvInitialize(const uint64_t& aRootLayerTreeId) override { return false; }
   virtual bool RecvRequestOverfill() override { return true; }
   virtual bool RecvWillClose() override { return true; }
   virtual bool RecvPause() override { return true; }
   virtual bool RecvResume() override { return true; }
-  virtual bool RecvNotifyHidden(const uint64_t& id) override;
-  virtual bool RecvNotifyVisible(const uint64_t& id) override;
   virtual bool RecvNotifyChildCreated(const uint64_t& child) override;
   virtual bool RecvAdoptChild(const uint64_t& child) override { return false; }
   virtual bool RecvMakeSnapshot(const SurfaceDescriptor& aInSnapshot,
                                 const gfx::IntRect& aRect) override
   { return true; }
   virtual bool RecvFlushRendering() override { return true; }
   virtual bool RecvForcePresent() override { return true; }
   virtual bool RecvNotifyRegionInvalidated(const nsIntRegion& aRegion) override { return true; }
@@ -2392,44 +2389,25 @@ CompositorBridgeParent::SendAsyncMessage
 
 bool
 CompositorBridgeParent::IsSameProcess() const
 {
   return OtherPid() == base::GetCurrentProcId();
 }
 
 bool
-CrossProcessCompositorBridgeParent::RecvNotifyHidden(const uint64_t& id)
-{
-  RefPtr<CompositorLRU> lru = CompositorLRU::GetSingleton();
-  lru->Add(this, id);
-  return true;
-}
-
-bool
-CrossProcessCompositorBridgeParent::RecvNotifyVisible(const uint64_t& id)
-{
-  RefPtr<CompositorLRU> lru = CompositorLRU::GetSingleton();
-  lru->Remove(this, id);
-  return true;
-}
-
-bool
 CrossProcessCompositorBridgeParent::RecvRequestNotifyAfterRemotePaint()
 {
   mNotifyAfterRemotePaint = true;
   return true;
 }
 
 void
 CrossProcessCompositorBridgeParent::ActorDestroy(ActorDestroyReason aWhy)
 {
-  RefPtr<CompositorLRU> lru = CompositorLRU::GetSingleton();
-  lru->Remove(this);
-
   // We must keep this object alive untill the code handling message
   // reception is finished on this thread.
   MessageLoop::current()->PostTask(NewRunnableMethod(this, &CrossProcessCompositorBridgeParent::DeferredDestroy));
 }
 
 PLayerTransactionParent*
 CrossProcessCompositorBridgeParent::AllocPLayerTransactionParent(
   const nsTArray<LayersBackend>&,

--- a/gfx/layers/ipc/CompositorBridgeParent.h
+++ b/gfx/layers/ipc/CompositorBridgeParent.h
@@ -229,18 +229,16 @@ public:
   bool Bind(Endpoint<PCompositorBridgeParent>&& aEndpoint);
 
   virtual bool RecvInitialize(const uint64_t& aRootLayerTreeId) override;
   virtual bool RecvGetFrameUniformity(FrameUniformityData* aOutData) override;
   virtual bool RecvRequestOverfill() override;
   virtual bool RecvWillClose() override;
   virtual bool RecvPause() override;
   virtual bool RecvResume() override;
-  virtual bool RecvNotifyHidden(const uint64_t& id) override { return true; }
-  virtual bool RecvNotifyVisible(const uint64_t& id) override { return true; }
   virtual bool RecvNotifyChildCreated(const uint64_t& child) override;
   virtual bool RecvAdoptChild(const uint64_t& child) override;
   virtual bool RecvMakeSnapshot(const SurfaceDescriptor& aInSnapshot,
                                 const gfx::IntRect& aRect) override;
   virtual bool RecvFlushRendering() override;
   virtual bool RecvForcePresent() override;
 
   virtual bool RecvAcknowledgeCompositorUpdate(const uint64_t& aLayersId) override {

deleted file mode 100644
--- a/gfx/layers/ipc/CompositorLRU.cpp
+++ /dev/null
@@ -1,101 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- * vim: sw=2 ts=8 et :
- */
-/* 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/. */
-
-#include "CompositorLRU.h"
-
-#include "mozilla/ClearOnShutdown.h"
-#include "mozilla/DebugOnly.h"
-#include "mozilla/Preferences.h"
-#include "mozilla/unused.h"
-
-#include "CompositorBridgeParent.h"
-
-namespace mozilla {
-namespace layers {
-
-mozilla::StaticRefPtr<CompositorLRU> CompositorLRU::sSingleton;
-
-void
-CompositorLRU::Init()
-{
-  Unused << GetSingleton();
-}
-
-CompositorLRU*
-CompositorLRU::GetSingleton()
-{
-  if (sSingleton) {
-    return sSingleton;
-  }
-  sSingleton = new CompositorLRU();
-  ClearOnShutdown(&sSingleton);
-
-  return sSingleton;
-}
-
-CompositorLRU::CompositorLRU()
-{
-  mLRUSize = Preferences::GetUint("layers.compositor-lru-size", uint32_t(0));
-}
-
-CompositorLRU::~CompositorLRU()
-{
-}
-
-void
-CompositorLRU::Add(PCompositorBridgeParent* aCompositor, const uint64_t& aId)
-{
-  auto index = mLRU.IndexOf(std::make_pair(aCompositor, aId));
-  if (index != nsTArray<CompositorLayerPair>::NoIndex) {
-    return;
-  }
-
-  if (mLRUSize == 0) {
-    Unused << aCompositor->SendClearCachedResources(aId);
-    return;
-  }
-
-  if (mLRU.Length() == mLRUSize) {
-    CompositorLayerPair victim = mLRU.LastElement();
-    Unused << victim.first->SendClearCachedResources(victim.second);
-    mLRU.RemoveElement(victim);
-  }
-  mLRU.InsertElementAt(0, std::make_pair(aCompositor, aId));
-}
-
-void
-CompositorLRU::Remove(PCompositorBridgeParent* aCompositor, const uint64_t& aId)
-{
-  if (mLRUSize == 0) {
-    return;
-  }
-
-  auto index = mLRU.IndexOf(std::make_pair(aCompositor, aId));
-
-  if (index == nsTArray<PCompositorBridgeParent*>::NoIndex) {
-    return;
-  }
-
-  mLRU.RemoveElementAt(index);
-}
-
-void
-CompositorLRU::Remove(PCompositorBridgeParent* aCompositor)
-{
-  if (mLRUSize == 0) {
-    return;
-  }
-
-  for (int32_t i = mLRU.Length() - 1; i >= 0; --i) {
-    if (mLRU[i].first == aCompositor) {
-      mLRU.RemoveElementAt(i);
-    }
-  }
-}
-
-} // namespace layers
-} // namespace mozilla

deleted file mode 100644
--- a/gfx/layers/ipc/CompositorLRU.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
- * vim: sw=2 ts=8 et :
- */
-/* 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_CompositorLRU_h
-#define mozilla_CompositorLRU_h
-
-#include "mozilla/StaticPtr.h"
-
-#include "nsISupportsImpl.h"
-#include "nsTArray.h"
-
-#include <utility>
-
-namespace mozilla {
-namespace layers {
-
-class PCompositorBridgeParent;
-
-class CompositorLRU final
-{
-  typedef std::pair<PCompositorBridgeParent*, uint64_t> CompositorLayerPair;
-public:
-  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorLRU)
-
-  static void Init();
-  static CompositorLRU* GetSingleton();
-
-  /**
-   * Adds the (PCompositorBridgeParent, LayerId) pair to the LRU pool. If
-   * the pool size grows over mLRUSize, the oldest PCompositorBridgeParent
-   * is evicted.
-   */
-  void Add(PCompositorBridgeParent* aCompositor, const uint64_t& id);
-
-  /**
-   * Remove the (PCompositorBridgeParent, LayersId) pair from the LRU pool.
-   */
-  void Remove(PCompositorBridgeParent* aCompositor, const uint64_t& id);
-
-  /**
-   * Remove all PCompositorBridgeParents from the LRU pool.
-   */
-  void Remove(PCompositorBridgeParent* aCompositor);
-
-private:
-  static StaticRefPtr<CompositorLRU> sSingleton;
-
-  CompositorLRU();
-  ~CompositorLRU();
-  uint32_t mLRUSize;
-  nsTArray<CompositorLayerPair> mLRU;
-};
-
-} // namespace layers
-} // namespace mozilla
-
-#endif // mozilla_CompositorLRU_h

--- a/gfx/layers/ipc/PCompositorBridge.ipdl
+++ b/gfx/layers/ipc/PCompositorBridge.ipdl
@@ -137,24 +137,16 @@ parent:
   // The child is about to be destroyed, so perform any necessary cleanup.
   sync WillClose();
 
   // Pause/resume the compositor. These are intended to be used on mobile, when
   // the compositor needs to pause/resume in lockstep with the application.
   sync Pause();
   sync Resume();
 
-  // The child layer tree is hidden. id is the layers id of the child
-  // layer tree.
-  async NotifyHidden(uint64_t id);
-
-  // The child layer tree is visible. id is the layers id of the child
-  // layer tree.
-  async NotifyVisible(uint64_t id);
-
   async NotifyChildCreated(uint64_t id);
   async AdoptChild(uint64_t id);
 
   // Make a snapshot of the content that would have been drawn to our
   // render target at the time this message is received.  If the size
   // or format of |inSnapshot| doesn't match our render target,
   // results are undefined.
   //

--- a/gfx/layers/moz.build
+++ b/gfx/layers/moz.build
@@ -153,17 +153,16 @@ EXPORTS.mozilla.layers += [
     'Effects.h',
     'ImageDataSerializer.h',
     'ipc/APZChild.h',
     'ipc/AsyncTransactionTracker.h',
     'ipc/CompositableForwarder.h',
     'ipc/CompositableTransactionParent.h',
     'ipc/CompositorBridgeChild.h',
     'ipc/CompositorBridgeParent.h',
-    'ipc/CompositorLRU.h',
     'ipc/CompositorThread.h',
     'ipc/FenceUtils.h',
     'ipc/GonkNativeHandle.h',
     'ipc/GonkNativeHandleUtils.h',
     'ipc/ImageBridgeChild.h',
     'ipc/ImageBridgeParent.h',
     'ipc/ImageContainerParent.h',
     'ipc/ISurfaceAllocator.h',
@@ -341,17 +340,16 @@ UNIFIED_SOURCES += [
     'ImageDataSerializer.cpp',
     'ImageLayers.cpp',
     'ipc/APZChild.cpp',
     'ipc/AsyncTransactionTracker.cpp',
     'ipc/CompositableTransactionParent.cpp',
     'ipc/CompositorBench.cpp',
     'ipc/CompositorBridgeChild.cpp',
     'ipc/CompositorBridgeParent.cpp',
-    'ipc/CompositorLRU.cpp',
     'ipc/CompositorThread.cpp',
     'ipc/FenceUtils.cpp',
     'ipc/ImageBridgeChild.cpp',
     'ipc/ImageBridgeParent.cpp',
     'ipc/ImageContainerParent.cpp',
     'ipc/ISurfaceAllocator.cpp',
     'ipc/LayerAnimationUtils.cpp',
     'ipc/LayerTransactionChild.cpp',

--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -120,17 +120,16 @@ using namespace mozilla::system;
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/IMEStateManager.h"
 #include "nsDocument.h"
 #include "mozilla/dom/HTMLVideoElement.h"
 #include "CameraPreferences.h"
 #include "TouchManager.h"
 #include "MediaDecoder.h"
 #include "MediaPrefs.h"
-#include "mozilla/layers/CompositorLRU.h"
 #include "mozilla/dom/devicestorage/DeviceStorageStatics.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/StaticPresData.h"
 #include "mozilla/dom/WebIDLGlobalNameHash.h"
 
 #ifdef MOZ_B2G_BT
 #include "mozilla/dom/BluetoothUUID.h"
 #endif
@@ -305,18 +304,16 @@ nsLayoutStatics::Initialize()
   nsStyleContext::Initialize();
   mozilla::LayerAnimationInfo::Initialize();
 #endif
 
   MediaDecoder::InitStatics();
 
   PromiseDebugging::Init();
 
-  layers::CompositorLRU::Init();
-
   mozilla::dom::devicestorage::DeviceStorageStatics::Initialize();
 
   mozilla::dom::WebCryptoThreadPool::Initialize();
 
 #ifdef MOZ_STYLO
   Servo_Initialize();
 #endif
 

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -4594,19 +4594,16 @@ pref("layers.shared-buffer-provider.enab
 
 // Force all possible layers to be always active layers
 pref("layers.force-active", false);
 
 // Never use gralloc surfaces, even when they're available on this
 // platform and are the optimal surface type.
 pref("layers.gralloc.disable", false);
 
-// Don't use compositor-lru on this platform
-pref("layers.compositor-lru-size", 0);
-
 // Enable/Disable the geolocation API for content
 pref("geo.enabled", true);
 
 // Timeout for outbound network geolocation provider XHR
 pref("geo.wifi.xhr.timeout", 60000);
 
 // Enable/Disable the orientation API for content
 pref("device.sensors.enabled", true);