Revert: Remove WindowTreeClientDelegate::GetCaptureClient() and WindowTreeClient::GetCaptureClient()

ui/views/mus/mus_client.cc

Index: ui/views/mus/mus_client.cc
diff --git a/ui/views/mus/mus_client.cc b/ui/views/mus/mus_client.cc
index 3d40563ea0eb57b0fa277fa4df57aee6f2dbe657..a30260dd0fd766fb89418d966ff22f24fa0e14ef 100644
--- a/ui/views/mus/mus_client.cc
+++ b/ui/views/mus/mus_client.cc
@@ -33,6 +33,7 @@
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 #include "ui/views/widget/widget_delegate.h"
+#include "ui/wm/core/capture_controller.h"
 #include "ui/wm/core/wm_state.h"
 
 // Widget::InitParams::Type must match that of ui::mojom::WindowType.
@@ -271,6 +272,10 @@
     observer.OnWindowManagerFrameValuesChanged();
 }
 
+aura::client::CaptureClient* MusClient::GetCaptureClient() {
+  return wm::CaptureController::Get();
+}
+
 aura::PropertyConverter* MusClient::GetPropertyConverter() {
   return property_converter_.get();
 }