First shot at implementing drag&drop for Aura

ui/aura_shell/aura_shell.gyp

 # Copyright (c) 2011 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
 
   'targets': [
@@ skipping 25 matching lines @@
         'default_container_event_filter.cc',
         'default_container_event_filter.h',
         'default_container_layout_manager.cc',
         'default_container_layout_manager.h',
         'desktop_background_view.cc',
         'desktop_background_view.h',
         'desktop_event_filter.cc',
         'desktop_event_filter.h',
         'desktop_layout_manager.cc',
         'desktop_layout_manager.h',
+        'drag_drop_controller.cc',
+        'drag_drop_controller.h',
         'launcher/app_launcher_button.cc',
         'launcher/app_launcher_button.h',
         'launcher/launcher.cc',
         'launcher/launcher.h',
         'launcher/launcher_model.cc',
         'launcher/launcher_model.h',
         'launcher/launcher_model_observer.h',
         'launcher/launcher_types.h',
         'launcher/launcher_view.cc',
         'launcher/launcher_view.h',
@@ skipping 54 matching lines @@
         '../ui.gyp:ui',
         '../ui.gyp:ui_resources',
         '../ui.gyp:ui_resources_standard',
         '../aura/aura.gyp:aura',
         '../aura/aura.gyp:test_support_aura',
         'aura_shell',
       ],
       'sources': [
         'default_container_layout_manager_unittest.cc',
         'desktop_event_filter_unittest.cc',
+        'drag_drop_controller_unittest.cc',
         'launcher/launcher_model_unittest.cc',
         'launcher/view_model_unittest.cc',
         'launcher/view_model_utils_unittest.cc',
         'run_all_unittests.cc',
         'stacking_controller_unittest.cc',
         'test_suite.cc',
         'test_suite.h',
         'toplevel_layout_manager_unittest.cc',
         'toplevel_window_event_filter_unittest.cc',
         'workspace_controller_unittest.cc',
@@ skipping 50 matching lines @@
         '../../views/views.gyp:views_desktop',
         '../../views/views.gyp:views_desktop_lib',
         '../../views/views.gyp:views_unittests',
         '../aura/aura.gyp:*',
         '../gfx/compositor/compositor.gyp:*',
         'aura_shell_exe',
       ],
     },
   ],
 }