--- a/gfx/layers/PaintThread.cpp
+++ b/gfx/layers/PaintThread.cpp
@@ -286,16 +286,20 @@ PaintThread::AsyncPrepareBuffer(Composit
 
 void
 PaintThread::PaintContents(CapturedPaintState* aState,
                            PrepDrawTargetForPaintingCallback aCallback)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aState);
 
+  if (gfxPrefs::LayersOMTPDumpCapture() && aState->mCapture) {
+    aState->mCapture->Dump();
+  }
+
   RefPtr<CompositorBridgeChild> cbc(CompositorBridgeChild::Get());
   RefPtr<CapturedPaintState> state(aState);
 
   cbc->NotifyBeginAsyncPaint(state);
 
   RefPtr<PaintThread> self = this;
   RefPtr<Runnable> task = NS_NewRunnableFunction("PaintThread::PaintContents",
     [self, cbc, state, aCallback]() -> void
@@ -356,16 +360,20 @@ PaintThread::AsyncPaintContents(Composit
 }
 
 void
 PaintThread::PaintTiledContents(CapturedTiledPaintState* aState)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aState);
 
+  if (gfxPrefs::LayersOMTPDumpCapture() && aState->mCapture) {
+    aState->mCapture->Dump();
+  }
+
   RefPtr<CompositorBridgeChild> cbc(CompositorBridgeChild::Get());
   RefPtr<CapturedTiledPaintState> state(aState);
 
   cbc->NotifyBeginAsyncPaint(state);
 
   RefPtr<PaintThread> self = this;
   RefPtr<Runnable> task = NS_NewRunnableFunction("PaintThread::PaintTiledContents",
     [self, cbc, state]() -> void

--- a/gfx/thebes/gfxPrefs.h
+++ b/gfx/thebes/gfxPrefs.h
@@ -610,16 +610,17 @@ private:
   DECL_GFX_PREF(Once, "layers.mlgpu.enable-clear-view",        AdvancedLayersEnableClearView, bool, true);
   DECL_GFX_PREF(Once, "layers.mlgpu.enable-cpu-occlusion",     AdvancedLayersEnableCPUOcclusion, bool, true);
   DECL_GFX_PREF(Once, "layers.mlgpu.enable-depth-buffer",      AdvancedLayersEnableDepthBuffer, bool, false);
   DECL_GFX_PREF(Live, "layers.mlgpu.enable-invalidation",      AdvancedLayersUseInvalidation, bool, true);
   DECL_GFX_PREF(Once, "layers.mlgpu.enable-on-windows7",       AdvancedLayersEnableOnWindows7, bool, false);
   DECL_GFX_PREF(Once, "layers.mlgpu.enable-container-resizing", AdvancedLayersEnableContainerResizing, bool, true);
   DECL_GFX_PREF(Once, "layers.offmainthreadcomposition.force-disabled", LayersOffMainThreadCompositionForceDisabled, bool, false);
   DECL_GFX_PREF(Live, "layers.offmainthreadcomposition.frame-rate", LayersCompositionFrameRate, int32_t,-1);
+  DECL_GFX_PREF(Live, "layers.omtp.dump-capture",              LayersOMTPDumpCapture, bool, false);
   DECL_GFX_PREF(Live, "layers.omtp.paint-workers",             LayersOMTPPaintWorkers, int32_t, 1);
   DECL_GFX_PREF(Live, "layers.omtp.release-capture-on-main-thread", LayersOMTPReleaseCaptureOnMainThread, bool, false);
   DECL_GFX_PREF(Live, "layers.orientation.sync.timeout",       OrientationSyncMillis, uint32_t, (uint32_t)0);
   DECL_GFX_PREF(Once, "layers.prefer-opengl",                  LayersPreferOpenGL, bool, false);
   DECL_GFX_PREF(Live, "layers.progressive-paint",              ProgressivePaint, bool, false);
   DECL_GFX_PREF(Live, "layers.shared-buffer-provider.enabled", PersistentBufferProviderSharedEnabled, bool, false);
   DECL_GFX_PREF(Live, "layers.single-tile.enabled",            LayersSingleTileEnabled, bool, true);
   DECL_GFX_PREF(Live, "layers.force-synchronous-resize",       LayersForceSynchronousResize, bool, true);