mus Window Server: implement event capture

components/mus/ws/test_change_tracker.cc

Index: components/mus/ws/test_change_tracker.cc
diff --git a/components/mus/ws/test_change_tracker.cc b/components/mus/ws/test_change_tracker.cc
index 6a7100c8e92d114254f5be37146009aac05a7200..8416f9594909de6203005b952b3b2a98d21d4d4a 100644
--- a/components/mus/ws/test_change_tracker.cc
+++ b/components/mus/ws/test_change_tracker.cc
@@ -47,6 +47,10 @@ std::string ChangeToDescription1(const Change& change) {
       return base::StringPrintf("OnUnembed window=%s",
                                 WindowIdToString(change.window_id).c_str());
 
+    case CHANGE_TYPE_LOST_CAPTURE:
+      return base::StringPrintf("OnLostCapture window=%s",
+                                WindowIdToString(change.window_id).c_str());
+
     case CHANGE_TYPE_NODE_ADD_TRANSIENT_WINDOW:
       return base::StringPrintf("AddTransientWindow parent = %s child = %s",
                                 WindowIdToString(change.window_id).c_str(),
@@ -258,6 +262,13 @@ void TestChangeTracker::OnTransientWindowRemoved(Id window_id,
   AddChange(change);
 }
 
+void TestChangeTracker::OnLostCapture(Id window_id) {
+  Change change;
+  change.type = CHANGE_TYPE_LOST_CAPTURE;
+  change.window_id = window_id;
+  AddChange(change);
+}
+
 void TestChangeTracker::OnWindowViewportMetricsChanged(
     mojom::ViewportMetricsPtr old_metrics,
     mojom::ViewportMetricsPtr new_metrics) {