new file mode 100644
--- /dev/null
+++ b/layout/ipc/jar.mn
@@ -0,0 +1,4 @@
+toolkit.jar:
+        content/global/test-ipcbrowser.xul (test-ipcbrowser.xul)
+        content/global/test-ipcbrowser-chrome.js (test-ipcbrowser-chrome.js)
+        content/global/test-ipcbrowser-content.js (test-ipcbrowser-content.js)

new file mode 100644
--- /dev/null
+++ b/layout/ipc/test-ipcbrowser-chrome.js
@@ -0,0 +1,115 @@
+function init() {
+    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;
+}
+
+// Functions affecting the content window.
+
+function loadURL(url) {
+    browser().setAttribute('src', url);
+}
+
+function scrollContentBy(dx, dy) {
+    messageManager.sendAsyncMessage("scrollBy",
+                                    { dx: dx, dy: dy });
+
+}
+
+function scrollContentTo(x, y) {
+    messageManager.sendAsyncMessage("scrollTo",
+                                    { x: x, y: y });
+}
+
+function setContentViewport(w, h) {
+    messageManager.sendAsyncMessage("setViewport",
+                                    { w: w, h: h });
+}
+
+function setContentDisplayPort(x, y, w, h) {
+    messageManager.sendAsyncMessage("setDisplayPort",
+                                    { x: x, y: y, w: w, h: h });
+}
+
+function setContentResolution(xres, yres) {
+    messageManager.sendAsyncMessage("setResolution",
+                                    { xres: xres, yres: yres });
+}
+
+// Functions affecting <browser>.
+
+function scrollViewportBy(dx, dy) {
+    frameLoader().scrollViewportBy(dx, dy);
+}
+
+function scrollViewportTo(x, y) {
+    frameLoader().scrollViewportTo(x, y);
+}
+
+function setViewportScale(xs, ys) {
+    frameLoader().setViewportScale(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) {
+        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;
+
+        frameLoader().scrollViewportBy(ddx, ddy);
+
+        if (!sentScrollBy && 100 <= (now - start)) {
+            messageManager.sendAsyncMessage("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);
+            frameLoader().scrollViewportBy(fixupDx, fixupDy);
+
+            scrolling = false;
+            removeEventListener("MozBeforePaint", nudgeScroll, false);
+        }
+        else {
+            mozRequestAnimationFrame();
+        }
+
+        prevNow = now;
+    }
+
+    nudgeScroll(start);
+    addEventListener("MozBeforePaint",
+                     function (e) { nudgeScroll(e.timeStamp); },
+                     false);
+    mozRequestAnimationFrame();
+}

new file mode 100644
--- /dev/null
+++ b/layout/ipc/test-ipcbrowser-content.js
@@ -0,0 +1,59 @@
+function windowUtils() {
+    return content.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
+               .getInterface(Components.interfaces.nsIDOMWindowUtils);
+}
+
+function recvSetViewport(w, h) {
+
+    dump("setting viewport to "+ w +"x"+ h +"\n");
+
+    windowUtils().setCSSViewport(w, h);
+}
+
+function recvSetDisplayPort(x, y, w, h) {
+
+    dump("setting displayPort to <"+ x +", "+ y +", "+ w +", "+ h +">\n");
+
+    windowUtils().setDisplayPort(x, y, w, h);
+}
+
+function recvSetResolution(xres, yres) {
+
+    dump("setting xres="+ xres +" yres="+ yres +"\n");
+
+    windowUtils().setResolution(xres, yres);
+}
+
+function recvScrollBy(dx, dy) {
+    content.scrollBy(dx, dy);
+}
+
+function recvScrollTo(x, y) {
+    content.scrollTo(x, y);
+}
+
+addMessageListener(
+    "setViewport",
+    function (m) { recvSetViewport(m.json.w, m.json.h); }
+);
+
+addMessageListener(
+    "setDisplayPort",
+    function (m) { recvSetDisplayPort(m.json.x, m.json.y,
+                                      m.json.w, m.json.h); }
+);
+
+addMessageListener(
+    "setResolution",
+    function (m) { recvSetResolution(m.json.xres, m.json.yres); }
+);
+
+addMessageListener(
+    "scrollBy",
+    function(m) { recvScrollBy(m.json.dx, m.json.dy); }
+);
+
+addMessageListener(
+    "scrollTo",
+    function(m) { recvScrollTo(m.json.x, m.json.y); }
+);

new file mode 100644
--- /dev/null
+++ b/layout/ipc/test-ipcbrowser.xul
@@ -0,0 +1,74 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        width="800" height="800" orient="vertical"
+        onload="init()">
+  <script src="chrome://global/content/test-ipcbrowser-chrome.js"/>
+
+  <toolbar id="controls">
+    <toolbarbutton label="Back"/>
+    <toolbarbutton label="Forward"/>
+    <textbox onchange="loadURL(this.value)" flex="1"/>
+  </toolbar>
+  <toolbar>
+    <textbox id="scbDx" flex="1" value="0"/>
+    <textbox id="scbDy" flex="1" value="100"/>
+    <toolbarbutton
+       onclick="scrollContentBy(document.getElementById('scbDx').value,
+                                document.getElementById('scbDy').value);"
+       label="scrollBy"/>
+    <textbox id="sctX" flex="1" value="200"/>
+    <textbox id="sctY" flex="1" value="300"/>
+    <toolbarbutton
+       onclick="scrollContentTo(document.getElementById('sctX').value,
+                                document.getElementById('sctY').value);"
+       label="scrollTo"/>
+  </toolbar>
+  <toolbar>
+    <textbox id="vW" flex="1" value="600"/>
+    <textbox id="vH" flex="1" value="400"/>
+    <toolbarbutton
+       onclick="setContentViewport(document.getElementById('vW').value,
+                                   document.getElementById('vH').value);"
+       label="setViewport"/>
+    <textbox id="dX" flex="1" value="0"/>
+    <textbox id="dY" flex="1" value="0"/>
+    <textbox id="dW" flex="1" value="600"/>
+    <textbox id="dH" flex="1" value="600"/>
+    <toolbarbutton
+       onclick="setContentDisplayPort(document.getElementById('dX').value,
+                                      document.getElementById('dY').value,
+                                      document.getElementById('dW').value,
+                                      document.getElementById('dH').value);"
+       label="setDisplayPort"/>
+    <textbox id="xR" flex="1" value="2.0"/>
+    <textbox id="yR" flex="1" value="2.0"/>
+    <toolbarbutton
+       onclick="setContentResolution(document.getElementById('xR').value,
+                                     document.getElementById('yR').value);"
+       label="setResolution"/>
+  </toolbar>
+  <toolbar>
+    <textbox id="vsbX" flex="1" value="0"/>
+    <textbox id="vsbY" flex="1" value="100"/>
+    <toolbarbutton
+       onclick="scrollViewportBy(document.getElementById('vsbX').value,
+                                 document.getElementById('vsbY').value);"
+       label="scrollViewportBy"/>
+    <textbox id="vstX" flex="1" value="200"/>
+    <textbox id="vstY" flex="1" value="300"/>
+    <toolbarbutton
+       onclick="scrollViewportTo(document.getElementById('vstX').value,
+                                 document.getElementById('vstY').value);"
+       label="scrollViewportTo"/>
+    <textbox id="vsX" flex="1" value="2.0"/>
+    <textbox id="vsY" flex="1" value="2.0"/>
+    <toolbarbutton
+       onclick="setViewportScale(document.getElementById('vsX').value,
+                                 document.getElementById('vsY').value);"
+       label="setViewportScale"/>
+  </toolbar>
+
+  <browser type="content" src="http://people.mozilla.com/~cjones/anim.html" flex="1" id="content"
+           remote="true"/>
+</window>