diff -r 000000000000 -r 6474c204b198 content/canvas/src/DocumentRendererChild.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/canvas/src/DocumentRendererChild.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,90 @@
+/* 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 "mozilla/ipc/DocumentRendererChild.h"
+
+#include "base/basictypes.h"
+
+#include "gfx2DGlue.h"
+#include "gfxPattern.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/RefPtr.h"
+#include "nsPIDOMWindow.h"
+#include "nsIDOMWindow.h"
+#include "nsIDocShell.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsCSSParser.h"
+#include "nsPresContext.h"
+#include "nsCOMPtr.h"
+#include "nsColor.h"
+#include "gfxContext.h"
+#include "nsLayoutUtils.h"
+#include "nsContentUtils.h"
+#include "nsCSSValue.h"
+#include "nsRuleNode.h"
+#include "mozilla/gfx/Matrix.h"
+
+using namespace mozilla;
+using namespace mozilla::gfx;
+using namespace mozilla::ipc;
+
+DocumentRendererChild::DocumentRendererChild()
+{}
+
+DocumentRendererChild::~DocumentRendererChild()
+{}
+
+bool
+DocumentRendererChild::RenderDocument(nsIDOMWindow *window,
+                                      const nsRect& documentRect,
+                                      const mozilla::gfx::Matrix& transform,
+                                      const nsString& aBGColor,
+                                      uint32_t renderFlags,
+                                      bool flushLayout,
+                                      const nsIntSize& renderSize,
+                                      nsCString& data)
+{
+    if (flushLayout)
+        nsContentUtils::FlushLayoutForTree(window);
+
+    nsRefPtr<nsPresContext> presContext;
+    nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(window);
+    if (win) {
+        nsIDocShell* docshell = win->GetDocShell();
+        if (docshell) {
+            docshell->GetPresContext(getter_AddRefs(presContext));
+        }
+    }
+    if (!presContext)
+        return false;
+
+    nsCSSParser parser;
+    nsCSSValue bgColorValue;
+    if (!parser.ParseColorString(aBGColor, nullptr, 0, bgColorValue)) {
+        return false;
+    }
+
+    nscolor bgColor;
+    if (!nsRuleNode::ComputeColor(bgColorValue, presContext, nullptr, bgColor)) {
+        return false;
+    }
+
+    // Draw directly into the output array.
+    data.SetLength(renderSize.width * renderSize.height * 4);
+
+    RefPtr<DrawTarget> dt =
+        Factory::CreateDrawTargetForData(BackendType::CAIRO,
+                                         reinterpret_cast<uint8_t*>(data.BeginWriting()),
+                                         IntSize(renderSize.width, renderSize.height),
+                                         4 * renderSize.width,
+                                         SurfaceFormat::B8G8R8A8);
+    nsRefPtr<gfxContext> ctx = new gfxContext(dt);
+    ctx->SetMatrix(mozilla::gfx::ThebesMatrix(transform));
+
+    nsCOMPtr<nsIPresShell> shell = presContext->PresShell();
+    shell->RenderDocument(documentRect, renderFlags, bgColor, ctx);
+
+    return true;
+}