cros: Remove some OS platform ifdefs from ash

ash/test/content/test_shell_content_state.h

Index: ash/test/content/test_shell_content_state.h
diff --git a/ash/test/content/test_shell_content_state.h b/ash/test/content/test_shell_content_state.h
index ed15b78f50c88d0173e7c1f71c3f4d1cd7935f58..28869d14b79c2e54e89b4b14b3b346dc7927b2c3 100644
--- a/ash/test/content/test_shell_content_state.h
+++ b/ash/test/content/test_shell_content_state.h
@@ -21,11 +21,9 @@ class TestShellContentState : public ShellContentState {
  public:
   TestShellContentState();
 
-#if defined(OS_CHROMEOS)
   content::ScreenOrientationDelegate* screen_orientation_delegate() {
     return &orientation_delegate_;
   }
-#endif
 
  private:
   ~TestShellContentState() override;