[Chromecast] Turn CastContentWindow into an abstract interface.

chromecast/browser/test/cast_browser_test.h

Index: chromecast/browser/test/cast_browser_test.h
diff --git a/chromecast/browser/test/cast_browser_test.h b/chromecast/browser/test/cast_browser_test.h
index dfb25ebd02c1dfa2e537fc23e5e020529275f368..63acd6b4183410e35755bd825f4ff89b019abf51 100644
--- a/chromecast/browser/test/cast_browser_test.h
+++ b/chromecast/browser/test/cast_browser_test.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "chromecast/browser/cast_content_window.h"
 #include "content/public/test/browser_test.h"
 #include "content/public/test/browser_test_base.h"
 
@@ -18,14 +19,13 @@ class WebContents;
 namespace chromecast {
 namespace shell {
 
-class CastContentWindow;
-
 // This test allows for running an entire browser-process lifecycle per unit
 // test, using Chromecast's cast_shell. This starts up the shell, runs a test
 // case, then shuts down the entire shell.
 // Note that this process takes 7-10 seconds per test case on Chromecast, so
 // fewer test cases with more assertions are preferable.
-class CastBrowserTest : public content::BrowserTestBase {
+class CastBrowserTest : public content::BrowserTestBase,
+                        CastContentWindow::Delegate {
  protected:
   CastBrowserTest();
   ~CastBrowserTest() override;
@@ -39,6 +39,10 @@ class CastBrowserTest : public content::BrowserTestBase {
   content::WebContents* NavigateToURL(const GURL& url);
 
  private:
+  // CastContentWindow::Delegate implementation:
+  void OnWindowDestroyed() override;
+  void OnKeyEvent(const ui::KeyEvent& key_event) override;
+
   std::unique_ptr<CastContentWindow> window_;
   std::unique_ptr<content::WebContents> web_contents_;