diff -r 000000000000 -r 6474c204b198 gfx/layers/RenderTrace.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/RenderTrace.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * 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 "RenderTrace.h"
+
+// If rendertrace is off let's no compile this code
+#ifdef MOZ_RENDERTRACE
+#include "Layers.h"
+
+
+namespace mozilla {
+namespace layers {
+
+static int colorId = 0;
+
+static gfx3DMatrix GetRootTransform(Layer *aLayer) {
+  gfx3DMatrix layerTrans = aLayer->GetTransform();
+  layerTrans.ProjectTo2D();
+  if (aLayer->GetParent() != nullptr) {
+    return GetRootTransform(aLayer->GetParent()) * layerTrans;
+  }
+  return layerTrans;
+}
+
+void RenderTraceLayers(Layer *aLayer, const char *aColor, const gfx3DMatrix aRootTransform, bool aReset) {
+  if (!aLayer)
+    return;
+
+  gfx3DMatrix trans = aRootTransform * aLayer->GetTransform();
+  trans.ProjectTo2D();
+  nsIntRect clipRect = aLayer->GetEffectiveVisibleRegion().GetBounds();
+  gfxRect rect(clipRect.x, clipRect.y, clipRect.width, clipRect.height);
+  trans.TransformBounds(rect);
+
+  if (strcmp(aLayer->Name(), "ContainerLayer") != 0 &&
+      strcmp(aLayer->Name(), "ContainerLayerComposite") != 0) {
+    printf_stderr("%s RENDERTRACE %u rect #%02X%s %i %i %i %i\n",
+      aLayer->Name(), (int)PR_IntervalNow(),
+      colorId, aColor,
+      (int)rect.x, (int)rect.y, (int)rect.width, (int)rect.height);
+  }
+
+  colorId++;
+
+  for (Layer* child = aLayer->GetFirstChild();
+        child; child = child->GetNextSibling()) {
+    RenderTraceLayers(child, aColor, aRootTransform, false);
+  }
+
+  if (aReset) colorId = 0;
+}
+
+void RenderTraceInvalidateStart(Layer *aLayer, const char *aColor, const nsIntRect aRect) {
+  gfx3DMatrix trans = GetRootTransform(aLayer);
+  gfxRect rect(aRect.x, aRect.y, aRect.width, aRect.height);
+  trans.TransformBounds(rect);
+
+  printf_stderr("%s RENDERTRACE %u fillrect #%s %i %i %i %i\n",
+    aLayer->Name(), (int)PR_IntervalNow(),
+    aColor,
+    (int)rect.x, (int)rect.y, (int)rect.width, (int)rect.height);
+}
+void RenderTraceInvalidateEnd(Layer *aLayer, const char *aColor) {
+  // Clear with an empty rect
+  RenderTraceInvalidateStart(aLayer, aColor, nsIntRect());
+}
+
+void renderTraceEventStart(const char *aComment, const char *aColor) {
+  printf_stderr("%s RENDERTRACE %u fillrect #%s 0 0 10 10\n",
+    aComment, (int)PR_IntervalNow(), aColor);
+}
+
+void renderTraceEventEnd(const char *aComment, const char *aColor) {
+  printf_stderr("%s RENDERTRACE %u fillrect #%s 0 0 0 0\n",
+    aComment, (int)PR_IntervalNow(), aColor);
+}
+
+void renderTraceEventEnd(const char *aColor) {
+  renderTraceEventEnd("", aColor);
+}
+
+}
+}
+
+#endif
+