Add support for taking partial screenshot using touch

ash/wm/partial_screenshot_view.h

 // 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_PARTIAL_SCREENSHOT_VIEW_H_
 #define ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "ui/gfx/point.h"
@@ skipping 20 matching lines @@
   PartialScreenshotView(OverlayDelegate* overlay_delegate,
                         ScreenshotDelegate* screenshot_delegate);
   virtual ~PartialScreenshotView();
 
   // Initializes partial screenshot UI widget for |root_window|.
   void Init(aura::RootWindow* root_window);
 
   // Returns the currently selected region.
   gfx::Rect GetScreenshotRect() const;
 
+  void OnSelectionStarted(gfx::Point position);

[sadrul, 2013/03/25 22:13:24]

const gfx::Point&

[Yufeng Shen (Slow to review), 2013/03/25 22:38:44]

Done.

+  void OnSelectionChanged(gfx::Point position);

[sadrul, 2013/03/25 22:13:24]

ditto

[Yufeng Shen (Slow to review), 2013/03/25 22:38:44]

Done.

+  void OnSelectionFinished();
+
   // Overridden from views::View:
   virtual gfx::NativeCursor GetCursor(const ui::MouseEvent& event) OVERRIDE;
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
   virtual bool OnMousePressed(const ui::MouseEvent& event) OVERRIDE;
   virtual bool OnMouseDragged(const ui::MouseEvent& event) OVERRIDE;
   virtual bool OnMouseWheel(const ui::MouseWheelEvent& event) OVERRIDE;
   virtual void OnMouseReleased(const ui::MouseEvent& event) OVERRIDE;
 
+  // Overidden from EventHandler

[sadrul, 2013/03/25 22:13:24]

.. from ui::EventHandler:

[Yufeng Shen (Slow to review), 2013/03/25 22:38:44]

Done.

+  virtual void OnGestureEvent(ui::GestureEvent* event);
+
   bool is_dragging_;
   gfx::Point start_position_;
   gfx::Point current_position_;
 
   // The delegate to receive Cancel. No ownership.
   OverlayDelegate* overlay_delegate_;
 
   // ScreenshotDelegate to take the actual screenshot. No ownership.
   ScreenshotDelegate* screenshot_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(PartialScreenshotView);
 };
 
 }  // namespace ash
 
 #endif  // #ifndef ASH_WM_PARTIAL_SCREENSHOT_VIEW_H_