diff -r 000000000000 -r 6474c204b198 layout/ipc/test-ipcbrowser-chrome.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/ipc/test-ipcbrowser-chrome.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,131 @@
+/* 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/. */
+
+function init() {
+    enableAsyncScrolling();
+    messageManager.loadFrameScript(
+        "chrome://global/content/test-ipcbrowser-content.js", true
+    );
+}
+
+function browser() {
+    return document.getElementById("content");
+}
+
+function frameLoader() {
+    return browser().QueryInterface(Components.interfaces.nsIFrameLoaderOwner).frameLoader;
+}
+
+function viewManager() {
+    return frameLoader().QueryInterface(Components.interfaces.nsIContentViewManager);
+}
+
+function rootView() {
+    return viewManager().rootContentView;
+}
+
+function enableAsyncScrolling() {
+    frameLoader().renderMode = Components.interfaces.nsIFrameLoader.RENDER_MODE_ASYNC_SCROLL;
+}
+
+// Functions affecting the content window.
+
+function loadURL(url) {
+    browser().setAttribute('src', url);
+}
+
+function scrollContentBy(dx, dy) {
+    messageManager.broadcastAsyncMessage("scrollBy",
+                                         { dx: dx, dy: dy });
+
+}
+
+function scrollContentTo(x, y) {
+    messageManager.broadcastAsyncMessage("scrollTo",
+                                         { x: x, y: y });
+}
+
+function setContentViewport(w, h) {
+    messageManager.broadcastAsyncMessage("setViewport",
+                                         { w: w, h: h });
+}
+
+function setContentDisplayPort(x, y, w, h) {
+    messageManager.broadcastAsyncMessage("setDisplayPort",
+                                         { x: x, y: y, w: w, h: h });
+}
+
+function setContentResolution(xres, yres) {
+    messageManager.broadcastAsyncMessage("setResolution",
+                                         { xres: xres, yres: yres });
+}
+
+// Functions affecting <browser>.
+
+function scrollViewportBy(dx, dy) {
+    rootView().scrollBy(dx, dy);
+}
+
+function scrollViewportTo(x, y) {
+    rootView().scrollTo(x, y);
+}
+
+function setViewportScale(xs, ys) {
+    rootView().setScale(xs, ys);
+}
+
+var kDelayMs = 100;
+var kDurationMs = 250;
+var scrolling = false;
+function startAnimatedScrollBy(dx, dy) {
+    if (scrolling)
+        throw "don't interrupt me!";
+
+    scrolling = true;
+
+    var start = mozAnimationStartTime;
+    var end = start + kDurationMs;
+    // |- k| so that we do something in first invocation of nudge()
+    var prevNow = start - 20;
+    var accumDx = 0, accumDy = 0;
+
+    var sentScrollBy = false;
+    function nudgeScroll(now) {
+	if (!scrolling) {
+	    // we've been canceled
+	    return;
+	}
+        var ddx = dx * (now - prevNow) / kDurationMs;
+        var ddy = dy * (now - prevNow) / kDurationMs;
+
+        ddx = Math.min(dx - accumDx, ddx);
+        ddy = Math.min(dy - accumDy, ddy);
+        accumDx += ddx;
+        accumDy += ddy;
+
+        rootView().scrollBy(ddx, ddy);
+
+        if (!sentScrollBy && 100 <= (now - start)) {
+            messageManager.broadcastAsyncMessage("scrollBy",
+                                                 { dx: dx, dy: dy });
+            sentScrollBy = true;
+        }
+
+        if (now >= end || (accumDx >= dx && accumDy >= dy)) {
+            var fixupDx = Math.max(dx - accumDx, 0);
+            var fixupDy = Math.max(dy - accumDy, 0);
+            rootView().scrollBy(fixupDx, fixupDy);
+
+            scrolling = false;
+        }
+        else {
+            mozRequestAnimationFrame(nudgeScroll);
+        }
+
+        prevNow = now;
+    }
+
+    nudgeScroll(start);
+    mozRequestAnimationFrame(nudgeScroll);
+}