mash: Change CastConfigDelegate to a mojoified CastConfigClient.

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 41d6b6247421cfb9d6e448affe4665db559dab27..a8158d0ac883c27c5bea7c73517e3832a81d2757 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -9,6 +9,7 @@
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/accelerators/ash_focus_manager_factory.h"
 #include "ash/common/accessibility_delegate.h"
+#include "ash/common/cast_config_client_proxy.h"
 #include "ash/common/devtools/ash_devtools_css_agent.h"
 #include "ash/common/devtools/ash_devtools_dom_agent.h"
 #include "ash/common/focus_cycler.h"
@@ -42,6 +43,7 @@
 #include "ash/common/wm_root_window_controller.h"
 #include "ash/common/wm_window.h"
 #include "ash/public/cpp/shell_window_ids.h"
+#include "ash/public/interfaces/cast_config.mojom.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ -247,6 +249,8 @@ void WmShell::SetPaletteDelegateForTesting(
 
 WmShell::WmShell(std::unique_ptr<ShellDelegate> shell_delegate)
     : delegate_(std::move(shell_delegate)),
+      cast_config_client_(base::MakeUnique<CastConfigClientProxy>(
+          delegate_->GetShellConnector())),
       focus_cycler_(base::MakeUnique<FocusCycler>()),
       immersive_context_(base::MakeUnique<ImmersiveContextAsh>()),
       locale_notification_controller_(