[Refactor] Move code for painting the window header for browser windows out of ash

ash/ash.gyp

Index: ash/ash.gyp
diff --git a/ash/ash.gyp b/ash/ash.gyp
index b1f0e2533dcab0ca4ba694f890f27fb6c63014ba..8ef2a7b311ef466a6b3926703a85edee14080bb1 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -498,6 +498,8 @@
         'wm/coordinate_conversion.h',
         'wm/custom_frame_view_ash.cc',
         'wm/custom_frame_view_ash.h',
+        'wm/default_header_painter.cc',
+        'wm/default_header_painter.h',
         'wm/default_state.cc',
         'wm/default_state.h',
         'wm/default_window_resizer.cc',
@@ -517,7 +519,8 @@
         'wm/event_client_impl.h',
         'wm/frame_border_hit_test_controller.cc',
         'wm/frame_border_hit_test_controller.h',
-        'wm/header_painter.cc',
+        'wm/header_metrics.cc',
+        'wm/header_metrics.h',
         'wm/header_painter.h',
         'wm/gestures/long_press_affordance_handler.cc',
         'wm/gestures/long_press_affordance_handler.h',
@@ -941,11 +944,11 @@
         'wm/caption_buttons/frame_caption_button_container_view_unittest.cc',
         'wm/caption_buttons/frame_maximize_button_unittest.cc',
         'wm/custom_frame_view_ash_unittest.cc',
+        'wm/default_header_painter_unittest.cc',
         'wm/dock/docked_window_layout_manager_unittest.cc',
         'wm/dock/docked_window_resizer_unittest.cc',
         'wm/drag_window_resizer_unittest.cc',
         'wm/gestures/overview_gesture_handler_unittest.cc',
-        'wm/header_painter_unittest.cc',
         'wm/immersive_fullscreen_controller_unittest.cc',
         'wm/lock_state_controller_unittest.cc',
         'wm/maximize_mode/maximize_mode_window_manager_unittest.cc',