mash: Change CastConfigDelegate to a mojoified CastConfigClient.

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index b7adf68b69edb12a1230eb3f5a131ec648ae1cdd..1dff4ae3131b6042aa392e9ed7087d56236e5568 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -44,6 +44,7 @@ namespace ash {
 class AcceleratorController;
 class AccessibilityDelegate;
 class BrightnessControlDelegate;
+class CastConfigController;
 class FocusCycler;
 class ImmersiveContextAsh;
 class ImmersiveFullscreenController;
@@ -122,6 +123,8 @@ class ASH_EXPORT WmShell {
     return brightness_control_delegate_.get();
   }
 
+  CastConfigController* cast_config() { return cast_config_.get(); }
+
   FocusCycler* focus_cycler() { return focus_cycler_.get(); }
 
   KeyboardBrightnessControlDelegate* keyboard_brightness_control_delegate() {
@@ -479,6 +482,7 @@ class ASH_EXPORT WmShell {
   std::unique_ptr<AcceleratorController> accelerator_controller_;
   std::unique_ptr<AccessibilityDelegate> accessibility_delegate_;
   std::unique_ptr<BrightnessControlDelegate> brightness_control_delegate_;
+  std::unique_ptr<CastConfigController> cast_config_;
   std::unique_ptr<FocusCycler> focus_cycler_;
   std::unique_ptr<ImmersiveContextAsh> immersive_context_;
   std::unique_ptr<KeyboardBrightnessControlDelegate>