Added arrow key navigation to Overview Mode

ash/wm/overview/window_grid.h

Index: ash/wm/overview/window_grid.h
diff --git a/ash/wm/overview/window_grid.h b/ash/wm/overview/window_grid.h
new file mode 100644
index 0000000000000000000000000000000000000000..fe4bf780ccc21a98c4ef46edd122fd684f5a437c
--- /dev/null
+++ b/ash/wm/overview/window_grid.h
@@ -0,0 +1,135 @@
+// Copyright 2014 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 ASH_WM_OVERVIEW_WINDOW_GRID_H_
+#define ASH_WM_OVERVIEW_WINDOW_GRID_H_
+
+#include <vector>
+
+#include "ash/wm/overview/window_selector.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window_observer.h"
+
+namespace aura {
+class Window;
+}
+
+namespace views {
+class Widget;
+}
+
+namespace ash {
+
+class WindowSelectorItem;
+
+// Represents a grid of windows in the Overview Mode in a particular root
+// window, and manages a selection widget that can be moved with the arrow keys.
+// The idea behind the movement strategy is that it should be possible to access
+// any window pressing a given arrow key repeatedly.
+// +-------+  +-------+  +-------+
+// |   0   |  |   1   |  |   2   |
+// +-------+  +-------+  +-------+
+// +-------+  +-------+  +-------+
+// |   3   |  |   4   |  |   5   |
+// +-------+  +-------+  +-------+
+// +-------+
+// |   6   |
+// +-------+
+// Example sequences:
+//  - Going right to left
+//    0, 1, 2, 3, 4, 5, 6
+//  - Going "top" to "bottom"
+//    0, 3, 6, 1, 4, 2, 5
+// The selector is switched to the next window grid (if available) or wrapped if
+// it reaches the end of its movement sequence.
+class ASH_EXPORT WindowGrid : public aura::WindowObserver {
+ public:
+  WindowGrid(aura::Window* root_window,
+             const std::vector<aura::Window*>& window_list,
+             WindowSelector* window_selector);
+  virtual ~WindowGrid();
+
+  // Positions all the windows in the grid.
+  void PositionWindows(bool animate);
+
+  // Updates |selected_index_| according to the specified |direction| and calls
+  // MoveSelectionWidget(). Returns |true| if the new selection index is out of
+  // this window grid bounds.
+  bool Move(WindowSelector::Direction direction);
+
+  // Returns the target selected window, or NULL if there is none selected.
+  WindowSelectorItem* SelectedWindow() const;
+
+  // Returns true if a window is contained in any of the WindowSelectorItems
+  // this grid owns.
+  bool Contains(const aura::Window* window) const;
+
+  // Returns true if the grid has no more windows.
+  bool empty() const { return window_list_.empty(); }
+
+  // Returns how many window selector items are in the grid.
+  size_t size() const { return window_list_.size(); }
+
+  // Returns true if the selection widget is active.
+  bool is_selecting() const { return selection_widget_ != NULL; }
+
+  // Returns the root window in which the grid displays the windows.
+  const aura::Window* root_window() const { return root_window_; }
+
+  const std::vector<WindowSelectorItem*>& window_list() const {
+    return window_list_.get();
+  }
+
+  // aura::WindowObserver:
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE;
+  // TODO(nsatragno): Handle window bounds changed in WindowSelectorItem.
+  virtual void OnWindowBoundsChanged(aura::Window* window,
+                                     const gfx::Rect& old_bounds,
+                                     const gfx::Rect& new_bounds) OVERRIDE;
+
+ private:
+  friend class WindowSelectorTest;
+
+  // Internal function to initialize the selection widget.
+  void InitSelectionWidget(WindowSelector::Direction direction);
+
+  // Moves the selection widget to the specified |direction|.
+  void MoveSelectionWidget(WindowSelector::Direction direction,
+                           bool recreate_selection_widget,
+                           bool out_of_bounds);
+
+  // Moves the selection widget to the targeted window.
+  void MoveSelectionWidgetToTarget(bool animate);
+
+  // Returns the target bounds of the currently selected item.
+  const gfx::Rect GetSelectionBounds() const;
+
+  // Root window the grid is in.
+  aura::Window* root_window_;
+
+  // Pointer to the window selector that spawned this grid.
+  WindowSelector* window_selector_;
+
+  // Vector containing all the windows in this grid.
+  ScopedVector<WindowSelectorItem> window_list_;
+
+  // Vector containing the observed windows.
+  std::set<aura::Window*> observed_windows_;
+
+  // Widget that indicates to the user which is the selected window.
+  scoped_ptr<views::Widget> selection_widget_;
+
+  // Current selected window position.
+  size_t selected_index_;
+
+  // Number of columns in the grid.
+  size_t num_columns_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowGrid);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_OVERVIEW_WINDOW_GRID_H_