First shot at implementing drag&drop for Aura

ui/aura_shell/shell.h

Index: ui/aura_shell/shell.h
diff --git a/ui/aura_shell/shell.h b/ui/aura_shell/shell.h
index 4f872ab90aab9164a0eb81b9d4f26db6f0400271..14596190386fdc07db0f293ea92e3bc5f5c8db42 100644
--- a/ui/aura_shell/shell.h
+++ b/ui/aura_shell/shell.h
@@ -15,15 +15,26 @@
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "ui/aura/desktop_delegate.h"
+#include "ui/aura/drag_drop_controller.h"
 #include "ui/aura_shell/aura_shell_export.h"
 
 namespace aura {
+class MouseEvent;
 class Window;
 }
 namespace gfx {
+class Point;
 class Rect;
 }
 
+namespace ui {
+class OSExchangeData;
+}
+
+namespace views {
+class Widget;
+}
+
 namespace aura_shell {
 
 class Launcher;
@@ -35,7 +46,8 @@ class WorkspaceController;
 
 // Shell is a singleton object that presents the Shell API and implements the
 // Desktop's delegate interface.
-class AURA_SHELL_EXPORT Shell : public aura::DesktopDelegate {
+class AURA_SHELL_EXPORT Shell : public aura::DesktopDelegate,
+                                public aura::DragDropController {
  public:
   // Upon creation, the Shell sets itself as the Desktop's delegate, which takes
   // ownership of the Shell.
@@ -68,6 +80,14 @@ class AURA_SHELL_EXPORT Shell : public aura::DesktopDelegate {
   virtual void AddChildToDefaultParent(aura::Window* window) OVERRIDE;
   virtual aura::Window* GetTopmostWindowToActivate(
       aura::Window* ignore) const OVERRIDE;
+  virtual DragDropController* GetDragDropController() const OVERRIDE;
+
+  // Overridden from aura::DragDropController:
+  virtual void StartDragAndDrop(const ui::OSExchangeData& data,
+                                int operation,
+                                const gfx::Point& location) OVERRIDE;
+  virtual void DragUpdate(const aura::MouseEvent& event) OVERRIDE;
+  virtual void Drop(const aura::MouseEvent& event) OVERRIDE;
 
   static Shell* instance_;
 
@@ -81,6 +101,9 @@ class AURA_SHELL_EXPORT Shell : public aura::DesktopDelegate {
 
   scoped_ptr<internal::WorkspaceController> workspace_controller_;
 
+  const ui::OSExchangeData* drag_data_;
+  scoped_ptr<views::Widget> drag_widget_;
+
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };