OK, here's john's patch plus my sync stuff.

ui/views/widget/desktop_aura/desktop_root_window_host_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/desktop_aura/desktop_root_window_host_linux.h"
 
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xutil.h>
 
@@ skipping 433 matching lines @@
   return gfx::Rect();
 }
 
 gfx::Rect DesktopRootWindowHostLinux::GetWorkAreaBoundsInScreen() const {
   std::vector<int> value;
   if (ui::GetIntArrayProperty(x_root_window_, "_NET_WORKAREA", &value) &&
       value.size() >= 4) {
     return gfx::Rect(value[0], value[1], value[2], value[3]);
   }
 
-  // TODO(erg): As a fallback, we should return the bounds for the current
-  // monitor. However, that's pretty difficult and requires futzing with XRR.
-  NOTIMPLEMENTED();
-  return gfx::Rect();
+  // Fetch the geometry of the root window.
+  Window root;
+  int x, y;
+  unsigned int width, height;
+  unsigned int border_width, depth;
+  if (!XGetGeometry(xdisplay_, x_root_window_, &root, &x, &y,
+                    &width, &height, &border_width, &depth)) {
+    NOTIMPLEMENTED();
+    return gfx::Rect(0, 0, 10, 10);
+  }
+
+  return gfx::Rect(x, y, width, height);
 }
 
 void DesktopRootWindowHostLinux::SetShape(gfx::NativeRegion native_region) {
   // TODO(erg):
   NOTIMPLEMENTED();
 }
 
 void DesktopRootWindowHostLinux::Activate() {
   X11DesktopHandler::get()->ActivateWindow(xwindow_);
 }
@@ skipping 217 matching lines @@
   return bounds_;
 }
 
 void DesktopRootWindowHostLinux::SetBounds(const gfx::Rect& bounds) {
   bool origin_changed = bounds_.origin() != bounds.origin();
   bool size_changed = bounds_.size() != bounds.size();
   XWindowChanges changes = {0};
   unsigned value_mask = 0;
 
   if (size_changed) {
+    // X11 will send an XError at our process if have a 0 sized window.
+    DCHECK_GT(bounds.width(), 0);
+    DCHECK_GT(bounds.height(), 0);
+
     changes.width = bounds.width();
     changes.height = bounds.height();
     value_mask |= CWHeight | CWWidth;
   }
 
   if (origin_changed) {
     changes.x = bounds.x();
     changes.y = bounds.y();
     value_mask |= CWX | CWY;
   }
@@ skipping 396 matching lines @@
 DesktopRootWindowHost* DesktopRootWindowHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura,
     const gfx::Rect& initial_bounds) {
   return new DesktopRootWindowHostLinux(native_widget_delegate,
                                         desktop_native_widget_aura,
                                         initial_bounds);
 }
 
 }  // namespace views