Initial cut at multi-window resize code. There's still some TODOs, but

ash/wm/workspace/multi_window_resize_controller.h

Index: ash/wm/workspace/multi_window_resize_controller.h
diff --git a/ash/wm/workspace/multi_window_resize_controller.h b/ash/wm/workspace/multi_window_resize_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..d1c83a9f5675916464388eb2fe265bebee6fa2b3
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+++ b/ash/wm/workspace/multi_window_resize_controller.h
@@ -0,0 +1,145 @@
+// Copyright (c) 2012 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_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_
+#define ASH_WM_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_
+#pragma once
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/timer.h"
+#include "ui/gfx/rect.h"
+#include "ui/views/mouse_watcher.h"
+
+namespace aura {
+class Window;
+}
+
+namespace views {
+class Widget;
+}
+
+namespace ash {
+namespace internal {
+
+class WorkspaceWindowResizer;
+
+// Two directions resizes happen in.
+enum Direction {
+  TOP_BOTTOM,
+  LEFT_RIGHT,
+};
+
+// MultiWindowResizeController is responsible for determining and showing a
+// widget that allows resizing multiple windows at the same time.
+// MultiWindowResizeController is driven by WorkspaceEventFilter.
+class ASH_EXPORT MultiWindowResizeController :
+    public views::MouseWatcherListener {
+ public:
+  MultiWindowResizeController();
+  ~MultiWindowResizeController();

[Ben Goodger (Google), 2012/03/06 15:40:45]

virtual

+
+  // If necessary, shows the resize widget. |window| is the window the mouse
+  // is over, |component| the edge and |point| the location of the mouse.
+  void Show(aura::Window* window, int component, const gfx::Point& point);
+
+  // Hides the resize widget.
+  void Hide();
+
+  void set_grid_size(int grid_size) { grid_size_ = grid_size; }
+
+  // MouseWatcherListenre overrides:
+  virtual void MouseMovedOutOfHost() OVERRIDE;
+
+ private:
+  // Used to track the two resizable windows and direction.
+  struct ResizeWindows {
+    ResizeWindows();
+    ~ResizeWindows();
+
+    // Returns true if |other| equals this ResizeWindows.
+    bool Equals(const ResizeWindows& other) const;
+
+    // Returns true if this ResizeWindows is valid.
+    bool is_valid() const { return window1 && window2; }
+
+    // The left/top window to resize.
+    aura::Window* window1;
+
+    // Other window to resize.
+    aura::Window* window2;
+
+    // Direction
+    Direction direction;
+  };
+
+  class ResizeMouseWatcherHost;
+  class ResizeView;
+
+  // Returns a ResizeWindows based on the specified arguments. Use is_valid()
+  // to test if the return value is a valid multi window resize location.
+  ResizeWindows DetermineWindows(aura::Window* window,
+                                 int window_component,
+                                 const gfx::Point& point) const;
+
+  // Finds a window by edge (one of the constants HitTestCompat.
+  aura::Window* FindWindowByEdge(aura::Window* window_to_ignore,
+                                 int edge_want,
+                                 int x,
+                                 int y) const;
+
+  // Shows the widget immediately.
+  void ShowNow();
+
+  // Returns true if the widget is showing.
+  bool IsShowing() const;
+
+  // Initiates a resize.
+  void StartResize(const gfx::Point& screen_location);
+
+  // Resizes to the new location.
+  void Resize(const gfx::Point& screen_location);
+
+  // Completes the resize.
+  void CompleteResize();
+
+  // Cancels the resize.
+  void CancelResize();
+
+  // Returns the bounds for the resize widget.
+  gfx::Rect CalculateResizeWidgetBounds() const;
+
+  // Returns true if |screen_location| is over the resize windows (or the resize
+  // widget itself).
+  bool IsOverWindows(const gfx::Point& screen_location) const;
+
+  // Returns true if |screen_location| is over |window|.
+  bool IsOverWindow(aura::Window* window,
+                    const gfx::Point& screen_location) const;
+
+  // Windows and direction to resize.
+  ResizeWindows windows_;
+
+  // Timer used before showing.
+  base::OneShotTimer<MultiWindowResizeController> show_timer_;
+
+  views::Widget* resize_widget_;
+
+  // If non-null we're in a resize loop.
+  scoped_ptr<WorkspaceWindowResizer> window_resizer_;
+
+  // Bounds the widget was last shown at.
+  gfx::Rect show_bounds_;
+
+  // Size of the grid.
+  int grid_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(MultiWindowResizeController);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_WM_WORKSPACE_MULTI_WINDOW_RESIZE_CONTROLLER_H_