[Chromecast] Turn CastContentWindow into an abstract interface.

chromecast/browser/service/cast_service_simple.h

Index: chromecast/browser/service/cast_service_simple.h
diff --git a/chromecast/browser/service/cast_service_simple.h b/chromecast/browser/service/cast_service_simple.h
index f40cc867b2a96d9d3985a29695d9b231f40b0162..636fbeccb4dec584de116dc3e97bbab1d1b42f22 100644
--- a/chromecast/browser/service/cast_service_simple.h
+++ b/chromecast/browser/service/cast_service_simple.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "chromecast/browser/cast_content_window.h"
 #include "chromecast/service/cast_service.h"
 #include "url/gurl.h"
 
@@ -17,9 +18,9 @@ class WebContents;
 
 namespace chromecast {
 namespace shell {
-class CastContentWindow;
 
-class CastServiceSimple : public CastService {
+class CastServiceSimple : public CastService,
+                          public CastContentWindow::Delegate {
  public:
   CastServiceSimple(content::BrowserContext* browser_context,
                     PrefService* pref_service);
@@ -32,6 +33,10 @@ class CastServiceSimple : public CastService {
   void StartInternal() override;
   void StopInternal() override;
 
+  // CastContentWindow::Delegate implementation:
+  void OnWindowDestroyed() override;
+  void OnKeyEvent(const ui::KeyEvent& key_event) override;
+
  private:
   std::unique_ptr<CastContentWindow> window_;
   std::unique_ptr<content::WebContents> web_contents_;