mash: Move ShelfWindowWatcher[ItemDelegate] to ash/common.

ash/mus/bridge/wm_window_mus.cc

Index: ash/mus/bridge/wm_window_mus.cc
diff --git a/ash/mus/bridge/wm_window_mus.cc b/ash/mus/bridge/wm_window_mus.cc
index 0418d4068f557cbe8801f3ac57dfa786223f7687..692441249c55c3585fab6bdbe440e85c185d1e3c 100644
--- a/ash/mus/bridge/wm_window_mus.cc
+++ b/ash/mus/bridge/wm_window_mus.cc
@@ -359,6 +359,14 @@ ShelfItemDetails* WmWindowMus::GetShelfItemDetails() {
   return nullptr;
 }
 
+void WmWindowMus::SetShelfItemDetails(const ShelfItemDetails& details) {
+  NOTIMPLEMENTED();

[sky, 2016/08/03 21:36:59]

I encourage you to file bugs for these and reference them here.

[msw, 2016/08/03 21:51:27]

Done.

+}
+
+void WmWindowMus::ClearShelfItemDetails() {
+  NOTIMPLEMENTED();
+}
+
 const wm::WindowState* WmWindowMus::GetWindowState() const {
   return window_state_.get();
 }