Implement workspace scrubbing

ash/wm/workspace/workspace_manager.h

Index: ash/wm/workspace/workspace_manager.h
diff --git a/ash/wm/workspace/workspace_manager.h b/ash/wm/workspace/workspace_manager.h
index e59eada1c6ea9d7d1c4898926fc050fcfde8b101..79bf0acd3b891f050d3b27adf166674e859aff80 100644
--- a/ash/wm/workspace/workspace_manager.h
+++ b/ash/wm/workspace/workspace_manager.h
@@ -53,6 +53,11 @@ class Workspace;
 // are maximized and restored they are reparented to the right Window.
 class ASH_EXPORT WorkspaceManager : public ash::ShellObserver {
  public:
+  enum CycleDirection {
+    CYCLE_NEXT,
+    CYCLE_PREVIOUS
+  };
+
   explicit WorkspaceManager(aura::Window* viewport);
   virtual ~WorkspaceManager();
 
@@ -78,6 +83,11 @@ class ASH_EXPORT WorkspaceManager : public ash::ShellObserver {
   // when a new Window is being added.
   aura::Window* GetParentForNewWindow(aura::Window* window);
 
+  // Called by the workspace cycler to activate the next workspace in
+  // |direction|. Returns false if there are no more workspaces to cycle
+  // to in |direction|.
+  bool CycleToWorkspace(CycleDirection direction);
+
   // Starts the animation that occurs on first login.
   void DoInitialAnimation();