Moves resources used by ash/wm/common to ash/wm/common/resources

ash/shelf/shelf_widget.cc

Index: ash/shelf/shelf_widget.cc
diff --git a/ash/shelf/shelf_widget.cc b/ash/shelf/shelf_widget.cc
index 7ac803a2613ae155789bffe0ba4265db195a16a3..216b0901d32855775fe45832886cfcc803346162 100644
--- a/ash/shelf/shelf_widget.cc
+++ b/ash/shelf/shelf_widget.cc
@@ -25,6 +25,7 @@
 #include "ash/wm/window_properties.h"
 #include "ash/wm/workspace_controller.h"
 #include "grit/ash_resources.h"
+#include "grit/ash_wm_common_resources.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_observer.h"
@@ -451,7 +452,7 @@ void ShelfWidget::DelegateView::SetParentLayer(ui::Layer* layer) {
 void ShelfWidget::DelegateView::OnPaintBackground(gfx::Canvas* canvas) {
   ui::ResourceBundle* rb = &ui::ResourceBundle::GetSharedInstance();
   gfx::ImageSkia shelf_background =
-      *rb->GetImageSkiaNamed(IDR_ASH_SHELF_BACKGROUND);
+      *rb->GetImageSkiaNamed(IDR_ASH_WM_COMMON_SHELF_BACKGROUND);

[oshima, 2016/05/19 22:48:55]

It sounds a bit weird to have "shelf_background" in wm. How will this be used in
mus-wm?

We should have used solid layer instead of image for this because it's much more
efficient. If you want to use this for a non work area, maybe we should do that
in mash instead?

[sky, 2016/05/19 22:56:59]

DockedWindowLayoutManager uses it:
https://codereview.chromium.org/1994993003/diff/40001/ash/wm/common/dock/dock...
. I added the TODO in the resource file about this. I will revisit it later on.

   const bool horizontal = wm::IsHorizontalAlignment(shelf_->GetAlignment());
   if (!horizontal) {
     shelf_background = gfx::ImageSkiaOperations::CreateRotatedImage(