Add support for taking partial screenshot using touch

ash/wm/partial_screenshot_view.cc

 // 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.
 
 #include "ash/wm/partial_screenshot_view.h"
 
 #include <algorithm>
 
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/screenshot_delegate.h"
@@ skipping 61 matching lines @@
   virtual ~OverlayDelegate() {
     Shell::GetInstance()->overlay_filter()->Deactivate();
   }
 
   std::vector<views::Widget*> widgets_;
 
   DISALLOW_COPY_AND_ASSIGN(OverlayDelegate);
 };
 
 // static
-void PartialScreenshotView::StartPartialScreenshot(
+std::vector<PartialScreenshotView*>
+PartialScreenshotView::StartPartialScreenshot(
     ScreenshotDelegate* screenshot_delegate) {
+  std::vector<PartialScreenshotView*> views;
   OverlayDelegate* overlay_delegate = new OverlayDelegate();
   Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
   for (Shell::RootWindowList::iterator it = root_windows.begin();
        it != root_windows.end(); ++it) {
     PartialScreenshotView* new_view = new PartialScreenshotView(
         overlay_delegate, screenshot_delegate);
     new_view->Init(*it);
+    views.push_back(new_view);
   }
+  return views;
 }
 
 PartialScreenshotView::PartialScreenshotView(
     PartialScreenshotView::OverlayDelegate* overlay_delegate,
     ScreenshotDelegate* screenshot_delegate)
     : is_dragging_(false),
       overlay_delegate_(overlay_delegate),
       screenshot_delegate_(screenshot_delegate) {
 }
 
@@ skipping 128 matching lines @@
       OnSelectionFinished();
       break;
     default:
       break;
   }
 
   event->SetHandled();
 }
 
 }  // namespace ash