Add setVisibilityState API to WebFrameWidget

public/web/WebFrameWidget.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebFrameWidget_h
 #define WebFrameWidget_h
 
 #include "../platform/WebCommon.h"
+#include "../platform/WebPageVisibilityState.h"
 #include "public/web/WebWidget.h"
 
 namespace blink {
 
 class WebLocalFrame;
 class WebWidgetClient;
 
 class WebFrameWidget : public WebWidget {
 public:
     BLINK_EXPORT static WebFrameWidget* create(WebWidgetClient*, WebLocalFrame*);
+
+    // Set frame-level visibility state.

[dcheng, 2015/02/26 17:42:08]

So this says frame-level state, but the enum is called page visibility state. I
think this comment should be updated to describe how the whole page visibility
thing works in conjunction with OOPIF, and why this is needed.

[kenrb, 2015/02/26 18:08:52]

Done.

+    // FIXME: Is this necessary? Should WebViewImpl::setVisibilityState() somehow
+    // trickle down this notification instead?

[dcheng, 2015/02/26 17:42:08]

I think this FIXME is unnecessary.

[kenrb, 2015/02/26 18:08:52]

Ok. I think we need to invest some time to understand how visibility would work
better, but probably better just to file a bug.

+    virtual void setVisibilityState(WebPageVisibilityState visibilityState, bool isInitialState) { }
 };
 
 } // namespace blink
 
 #endif