Implement workspace scrubbing

ash/wm/workspace/workspace.cc

Index: ash/wm/workspace/workspace.cc
diff --git a/ash/wm/workspace/workspace.cc b/ash/wm/workspace/workspace.cc
index a2c03254b97e8606c15f5c9807a6ffd5e09057d9..4ccc2bc78c6d8e1cb483c1d5780ef7406184b078 100644
--- a/ash/wm/workspace/workspace.cc
+++ b/ash/wm/workspace/workspace.cc
@@ -58,6 +58,21 @@ aura::Window* Workspace::ReleaseWindow() {
   return window;
 }
 
+aura::Window* Workspace::GetActiveWindow() const {
+  aura::Window* active_window = wm::GetActiveWindow();

[sky, 2012/11/28 15:15:34]

Did you see my earlier comment on this? I believe this can be:
return window_->Contains(active_window) ? active_window : NULL;

at which point it might not be worth a method.

Also, this should return a const aura::Window*. If you need no const then the
method shouldn't be const either.

+  if (!active_window)
+    return NULL;
+
+  // Only return the active window if it is in this workspace.
+  aura::Window* window = active_window;
+  while (window) {
+    if (window == window_)
+      return active_window;
+    window = window->parent();
+  }
+  return NULL;
+}
+
 bool Workspace::ShouldMoveToPending() const {
   if (!is_maximized_)
     return false;