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..9ee17b73f0ee10fcf5e2e0946e7f27c8b61ff72e
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+++ b/ash/wm/overview/window_grid.h
@@ -0,0 +1,79 @@
+// 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"
+
+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.
+class WindowGrid {
+ public:
+  WindowGrid(aura::Window* root_window,
+             std::vector<WindowSelectorItem*> window_list);
+  ~WindowGrid();
+
+  // Moves the selection widget to the specified |direction|. Returns false if,
+  // after moving, the widget is out of bounds.
+  bool Move(WindowSelector::Direction direction);
+
+  // Positions all the windows in the grid. If a window pointer is invalid, the

[tdanderson, 2014/05/28 16:01:19]

Just reading this header file and not looking into window_grid.cc, I have no
idea what your second sentence means. Also, behaviour should always be defined,
even if that behaviour is "do nothing."

[Nina, 2014/05/29 17:12:24]

I'll consider that for future changes. I removed the comment because it didn't
make sense anymore.

+  // behavior is undefined.
+  void PositionWindows(bool animate);
+
+  // Removes |window| from the grid, if present. Returns true if this was the
+  // case, false if |window| was not found.

[tdanderson, 2014/05/28 16:01:19]

This comment needs to be updated since RemoveWindow() is returning a WSI* and
not a bool.

[Nina, 2014/05/29 17:12:24]

Done.

+  WindowSelectorItem* RemoveWindow(aura::Window* window);
+
+  // Returns the target selected window, or NULL if there is none selected.
+  WindowSelectorItem* SelectedWindow() const;
+
+  // Returns true if the grid no more windows.
+  bool empty() { return window_list_.empty(); }
+
+ private:
+  // Updates |selected_index_| according to the specified |direction|. Returns
+  // |true| if the new selection index is out of this window grid bounds.
+  bool MoveSelectedIndex(WindowSelector::Direction direction);
+
+  const gfx::Rect GetSelectionBounds() const;

[tdanderson, 2014/05/28 16:01:19]

Add documentation for this.

[Nina, 2014/05/29 17:12:24]

Done.

+
+  // Root window the grid is in.
+  aura::Window* root_window_;
+
+  // Vector containing all the windows in this grid.
+  std::vector<WindowSelectorItem*> window_list_;
+
+  // Widget that indicates the user which is the selected window.

[tdanderson, 2014/05/28 16:01:19]

to the user

[Nina, 2014/05/29 17:12:24]

Done.

+  scoped_ptr<views::Widget> selection_widget_;
+
+  // Current selected window position.
+  size_t selected_index_;
+
+  // Grid size.
+  size_t rows_;

[tdanderson, 2014/05/28 16:01:19]

I would prefer num_rows_ and num_columns_ to make the identifier names more
descriptive for people reading the code. When I see |rows_|, I assume it is some
sort of collection (e.g., rows_[0] would give me a pointer to a linked list
representing the items in the top row).

[Nina, 2014/05/29 17:12:24]

Done.

+  size_t columns_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowGrid);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_OVERVIEW_WINDOW_GRID_H_