Add WorkspaceObserver to observe changes in workspace state

ui/aura_shell/workspace/workspace_manager.h

 // Copyright (c) 2011 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.
 
 #ifndef UI_AURA_SHELL_WORKSPACE_WORKSPACE_MANAGER_H_
 #define UI_AURA_SHELL_WORKSPACE_WORKSPACE_MANAGER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/observer_list.h"
 #include "ui/aura_shell/aura_shell_export.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/size.h"
 
 namespace aura {
 class Window;
 }
 
 namespace gfx {
 class Point;
 class Rect;
 }
 
 namespace aura_shell {
 namespace internal {
 class Workspace;
+class WorkspaceObserver;
 
 // WorkspaceManager manages multiple workspaces in the desktop.
 class AURA_SHELL_EXPORT WorkspaceManager {
  public:
   explicit WorkspaceManager(aura::Window* viewport);
   virtual ~WorkspaceManager();
 
+  // Returns the viewport window this WorkspaceManager layouts
+  // workspaces on.
+  aura::Window* viewport() { return viewport_; }

[sky, 2011/11/02 03:57:49]

nit: this actually isn't a viewport. A viewport is generally the size of the
visible region. This is really the underlying window, maybe it should be called
content_window. See the graphic on the right side of
http://download.oracle.com/javase/1.4.2/docs/api/javax/swing/JScrollPane.html 
as well as Viewport in views/controls/scroll_view.cc .

Don't change it in this patch, but it would be good to fix at some point.

+
   // Create new workspace. Workspace objects are managed by
   // this WorkspaceManager. Deleting workspace will automatically
   // remove the workspace from the workspace_manager.
   Workspace* CreateWorkspace();
 
   // Returns the active workspace.
   Workspace* GetActiveWorkspace() const;
 
   // Returns the workspace that contanis the |window|.
   Workspace* FindBy(aura::Window* window) const;
@@ skipping 10 matching lines @@
   // Turn on/off overview mode.
   void SetOverview(bool overview);
   bool is_overview() const { return is_overview_; }
 
   // Rotate windows by moving |source| window to the position of |target|.
   void RotateWindows(aura::Window* source, aura::Window* target);
 
   // Sets the size of a single workspace (all workspaces have the same size).
   void SetWorkspaceSize(const gfx::Size& workspace_size);
 
+  // Adds/Removes workspace observer.
+  void AddObserver(WorkspaceObserver* observer);
+  void RemoveObserver(WorkspaceObserver* observer);
+
+  // Returns true if this workspace manager is laying out windows.
+  // LayoutManager for this workspace manager request must not modify

[sky, 2011/11/02 03:57:49]

How about replacing the second sentence with: 'When true the LayoutManager gives
windows their requested bounds.'

+  // the requested bounds in |SetChildBounds| when this flag is true.
+  bool layout_in_progress() const nj{ return layout_in_progress_; }

[sky, 2011/11/02 03:57:49]

remove 'nj'

+
+  // Sets the |layout_in_progress_| flag.
+  void set_layout_in_progress(bool layout_in_progress) {
+    layout_in_progress_ = layout_in_progress;
+  }
+
  private:
   friend class Workspace;
 
   void AddWorkspace(Workspace* workspace);
   void RemoveWorkspace(Workspace* workspace);
 
   // Sets the active workspace.
   void SetActiveWorkspace(Workspace* workspace);
 
   // Returns the bounds of the work are given |workspace_bounds|.
@@ skipping 11 matching lines @@
 
   std::vector<Workspace*> workspaces_;
 
   // The size of a single workspace. This is generally the same as the size of
   // monitor.
   gfx::Size workspace_size_;
 
   // True if the workspace manager is in overview mode.
   bool is_overview_;
 
+  // True if this layout manager is laying out windows.
+  bool layout_in_progress_;
+
+  ObserverList<WorkspaceObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(WorkspaceManager);
 };
 
 }  // namespace internal
 }  // namespace aura_shell
 
 #endif  // UI_AURA_SHELL_WORKSPACE_WORKSPACE_MANAGER_H_