Add support code to test the cast system tray item.

ash/system/cast/tray_cast.h

Index: ash/system/cast/tray_cast.h
diff --git a/ash/system/cast/tray_cast.h b/ash/system/cast/tray_cast.h
index 04a4bc28a802aebee55c40818e4a36ed0e16a31e..0b5b5e38079ea367f21b2e8dbcc7fabe65823ea2 100644
--- a/ash/system/cast/tray_cast.h
+++ b/ash/system/cast/tray_cast.h
@@ -18,12 +18,19 @@ class CastDetailedView;
 class CastDuplexView;
 }  // namespace tray
 
-class TrayCast : public SystemTrayItem, public ShellObserver {
+class ASH_EXPORT TrayCast : public SystemTrayItem, public ShellObserver {
  public:
   explicit TrayCast(SystemTray* system_tray);
   ~TrayCast() override;
 
  private:
+  // Helper/utility methods for testing.
+  friend class TrayCastTestAPI;
+  void StartCastForTest(const std::string& receiver_id);
+  void StopCastForTest();
+  views::View* default_view();

[achuithb, 2015/07/21 19:52:29]

You can inline the function here

[jdufault, 2015/07/21 20:21:31]

default_ is an incomplete type, so it cannot be converted to view::View*. 

[jdufault, 2015/07/21 20:22:24]

Oops, old comment. I converted the type using a cast.

[achuithb, 2015/07/21 20:30:17]

I'm really sorry, but I didn't expect there would be a cast. I thought you would
just need to return the variable, in which case this would be ok in the .h. 

Also, I think we would like to avoid reinterpret cast. Does static_cast not
work?

Let's move this back to the cc. So sorry for the back and forth.

[jdufault, 2015/07/21 20:48:53]

No worries, I've moved it back to the cc file.

Nope, static_cast didn't work because the types were unrelated via inheritance.

+  enum ChildViewIds { TRAY_VIEW = 1, SELECT_VIEW, CAST_VIEW };

[achuithb, 2015/07/21 19:52:29]

ChildViewId?

[jdufault, 2015/07/21 20:21:31]

Done.

+
   // Overridden from SystemTrayItem.
   views::View* CreateTrayView(user::LoginStatus status) override;
   views::View* CreateDefaultView(user::LoginStatus status) override;