The Wireframe Camera View displays a wireframe rendering of the Camera View.
To display the Camera View in wireframe mode, you can invoke the Hide OpenGL Camera View menu, press the F11 key, or right click on the Camera Window and choose Hide OpenGL View.
Note you can also draw the Camera view with hidden lines removed by right clicking on the Camera window and selecting the Draw Hidden Line context menu.
To toggle the OpenGL Shaded Camera View back on you can invoke the Show OpenGL Camera View menu, press the F11 key, or right click on the Camera Window and choose Show OpenGL Camera View.