Attempt 3: Makes managed mode constrain the height of windows so they don't

ash/wm/workspace/workspace_window_resizer.h

Index: ash/wm/workspace/workspace_window_resizer.h
diff --git a/ash/wm/workspace/workspace_window_resizer.h b/ash/wm/workspace/workspace_window_resizer.h
new file mode 100644
index 0000000000000000000000000000000000000000..d32b0be1e5571b39f67fc2f6e07fe580716e1cbd
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+++ b/ash/wm/workspace/workspace_window_resizer.h
@@ -0,0 +1,52 @@
+// 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_WINDOW_RESIZER_H_
+#define ASH_WM_WORKSPACE_WINDOW_RESIZER_H_
+#pragma once
+
+#include "ash/wm/window_resizer.h"
+#include "base/compiler_specific.h"
+
+namespace ash {
+namespace internal {
+
+// WindowResizer implementation for workspaces. This enforces that windows are
+// not allowed to vertically move or resize outside of the work area. As windows
+// are moved outside the work area they are shrunk. We remember the height of
+// the window before it was moved so that if the window is again moved up we
+// attempt to restore the old height.
+class ASH_EXPORT WorkspaceWindowResizer : public WindowResizer {
+ public:
+  WorkspaceWindowResizer(aura::Window* window,
+                         const gfx::Point& location,
+                         int window_component,
+                         int grid_size);
+  virtual ~WorkspaceWindowResizer();
+
+ protected:
+  // WindowResizer overrides:
+  virtual gfx::Rect GetBoundsForDrag(const gfx::Point& location) OVERRIDE;
+  virtual gfx::Rect GetFinalBounds() OVERRIDE;
+
+ private:
+  // Used to maintain the height of the window before we started collapsing it.
+  static void SetHeightBeforeObscured(aura::Window* window, int height);
+  static void ClearHeightBeforeObscured(aura::Window* window);
+  static int GetHeightBeforeObscured(aura::Window* window);
+
+  // Adjusts the bounds to enforce that windows are vertically contained in the
+  // work area.
+  void AdjustBounds(gfx::Rect* bounds) const;
+
+  // Returns true if the window touches the bottom of the work area.
+  bool WindowTouchesBottomOfScreen() const;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkspaceWindowResizer);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_WM_WORKSPACE_WINDOW_RESIZER_H_