Use the source display's pixel size as a mirror window's size.

ash/ash.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/chrome',
   },
   'includes': [
@@ skipping 46 matching lines @@
         'accelerators/accelerator_table.cc',
         'accelerators/accelerator_table.h',
         'accelerators/exit_warning_handler.cc',
         'accelerators/exit_warning_handler.h',
         'accelerators/focus_manager_factory.cc',
         'accelerators/focus_manager_factory.h',
         'accelerators/nested_dispatcher_controller.cc',
         'accelerators/nested_dispatcher_controller.h',
         'ash_constants.cc',
         'ash_constants.h',
-        'ash_root_window_transformer.cc',
-        'ash_root_window_transformer.h',
         'ash_switches.cc',
         'ash_switches.h',
         'cancel_mode.cc',
         'cancel_mode.h',
         'caps_lock_delegate.h',
         'caps_lock_delegate_stub.cc',
         'caps_lock_delegate_stub.h',
         'debug.cc',
         'debug.h',
         'desktop_background/desktop_background_controller.cc',
@@ skipping 19 matching lines @@
         'display/display_manager.h',
         'display/display_pref_util.h',
         'display/event_transformation_handler.cc',
         'display/event_transformation_handler.h',
         'display/mirror_window_controller.cc',
         'display/mirror_window_controller.h',
         'display/mouse_cursor_event_filter.cc',
         'display/mouse_cursor_event_filter.h',
         'display/output_configurator_animation.cc',
         'display/output_configurator_animation.h',
+        'display/root_window_transformers.cc',
+        'display/root_window_transformers.h',
         'display/screen_position_controller.cc',
         'display/screen_position_controller.h',
         'display/shared_display_edge_indicator.cc',
         'display/shared_display_edge_indicator.h',
         'drag_drop/drag_drop_controller.cc',
         'drag_drop/drag_drop_controller.h',
         'drag_drop/drag_drop_tracker.cc',
         'drag_drop/drag_drop_tracker.h',
         'drag_drop/drag_image_view.cc',
         'drag_drop/drag_image_view.h',
@@ skipping 505 matching lines @@
       ],
       'sources': [
         '../ui/compositor/test/layer_animator_test_controller.cc',
         '../ui/compositor/test/layer_animator_test_controller.h',
         '../ui/views/test/test_views_delegate.cc',
         '../ui/views/test/test_views_delegate.h',
         'accelerators/accelerator_controller_unittest.cc',
         'accelerators/accelerator_filter_unittest.cc',
         'accelerators/accelerator_table_unittest.cc',
         'accelerators/nested_dispatcher_controller_unittest.cc',
-        'ash_root_window_transformer_unittest.cc',
         'desktop_background/desktop_background_controller_unittest.cc',
         'dip_unittest.cc',
         'display/display_controller_unittest.cc',
         'display/display_error_dialog_unittest.cc',
         'display/display_info_unittest.cc',
+        'display/display_manager_unittest.cc',
         'display/mirror_window_controller_unittest.cc',
         'display/mouse_cursor_event_filter_unittest.cc',
-        'display/display_manager_unittest.cc',
+        'display/root_window_transformers_unittest.cc',
         'display/screen_position_controller_unittest.cc',
         'drag_drop/drag_drop_controller_unittest.cc',
         'drag_drop/drag_drop_tracker_unittest.cc',
         'extended_desktop_unittest.cc',
         'focus_cycler_unittest.cc',
         'keyboard_overlay/keyboard_overlay_delegate_unittest.cc',
         'keyboard_overlay/keyboard_overlay_view_unittest.cc',
         'launcher/launcher_model_unittest.cc',
         'launcher/launcher_navigator_unittest.cc',
         'launcher/launcher_tooltip_manager_unittest.cc',
@@ skipping 201 matching lines @@
             'shell/cocoa/app-Info.plist',
           ],
           'xcode_settings': {
             'INFOPLIST_FILE': 'shell/cocoa/app-Info.plist',
           },
         }],
       ],
     },
   ],
 }