mus: Implement ScreenMus::GetCursorScreenPoint().

components/mus/ws/window_tree.cc

Index: components/mus/ws/window_tree.cc
diff --git a/components/mus/ws/window_tree.cc b/components/mus/ws/window_tree.cc
index 863a3a13e61a2095581b0f08fac3b089e39daa76..60c540c83cb0ba776869339deb16b3386ae4a757 100644
--- a/components/mus/ws/window_tree.cc
+++ b/components/mus/ws/window_tree.cc
@@ -18,6 +18,7 @@
 #include "components/mus/ws/platform_display.h"
 #include "components/mus/ws/server_window.h"
 #include "components/mus/ws/server_window_observer.h"
+#include "components/mus/ws/user_display_manager.h"
 #include "components/mus/ws/window_manager_state.h"
 #include "components/mus/ws/window_server.h"
 #include "components/mus/ws/window_tree_binding.h"
@@ -669,6 +670,19 @@ WindowManagerState* WindowTree::GetWindowManagerStateForWindowManager() {
   return wms;
 }
 
+void WindowTree::GetCursorScreenPoint(
+    const GetCursorScreenPointCallback& callback) {
+  if (roots_.empty()) {

[Elliot Glaysher, 2016/04/18 20:21:37]

Is this empty roots thing a case we reasonably have to care about?

[sky, 2016/04/18 20:53:05]

Yes. It should be possible to query for the cursor location when a root hasn't
been created. I recommend routing the call to the windowserver, supply the id of
the user id and the WindowServer can then route to the appropriate
WindowManagerState. You'll want the WindowServer function to take a user id. If
the user id isn't active, return 0x0.

+    mojo::PointPtr p = mojo::Point::New();
+    p->x = 0;
+    p->y = 0;
+    callback.Run(std::move(p));
+  } else {
+    callback.Run(mojo::Point::From(
+        GetWindowManagerState(*roots_.begin())->GetCursorLocation()));
+  }
+}
+
 bool WindowTree::ShouldRouteToWindowManager(const ServerWindow* window) const {
   // If the client created this window, then do not route it through the WM.
   if (window->id().connection_id == id_)