Adds views::corewm::WMState to install common state

ui/views/corewm/transient_window_stacking_client.cc

Index: ui/views/corewm/transient_window_stacking_client.cc
diff --git a/ui/views/corewm/transient_window_stacking_client.cc b/ui/views/corewm/transient_window_stacking_client.cc
index 6a4f8ab25cb687344e91a59812c0ea1a18c1bc6c..e3373ffacf0d6462ce8406d68175748594cc78c3 100644
--- a/ui/views/corewm/transient_window_stacking_client.cc
+++ b/ui/views/corewm/transient_window_stacking_client.cc
@@ -68,7 +68,7 @@ TransientWindowStackingClient::TransientWindowStackingClient() {
 TransientWindowStackingClient::~TransientWindowStackingClient() {
 }
 
-void TransientWindowStackingClient::AdjustStacking(
+bool TransientWindowStackingClient::AdjustStacking(
     Window** child,
     Window** target,
     Window::StackDirection* direction) {
@@ -89,6 +89,7 @@ void TransientWindowStackingClient::AdjustStacking(
     }
     *target = siblings[target_i];
   }
+  return true;
 }
 
 }  // namespace corewm