Fire visibilityChange event on out-of-process iframes.

third_party/WebKit/Source/web/WebFrameWidgetImpl.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 100 matching lines @@
     bool caretOrSelectionRange(size_t* location, size_t* length) override;
     void setTextDirection(WebTextDirection) override;
     bool isAcceleratedCompositingActive() const override;
     void willCloseLayerTreeView() override;
     void didChangeWindowResizerRect() override;
     void didAcquirePointerLock() override;
     void didNotAcquirePointerLock() override;
     void didLosePointerLock() override;
 
     // WebFrameWidget implementation.
-    void setVisibilityState(WebPageVisibilityState, bool) override;
+    void setVisibilityState(WebPageVisibilityState) override;
     bool isTransparent() const override;
     void setIsTransparent(bool) override;
     void setBaseBackgroundColor(WebColor) override;
     void scheduleAnimation() override;
     CompositorProxyClient* createCompositorProxyClient() override;
 
     WebWidgetClient* client() const override { return m_client; }
 
     Frame* focusedCoreFrame() const;
 
@@ skipping 98 matching lines @@
     WebColor m_baseBackgroundColor;
 
     SelfKeepAlive<WebFrameWidgetImpl> m_selfKeepAlive;
 };
 
 DEFINE_TYPE_CASTS(WebFrameWidgetImpl, WebFrameWidget, widget, widget->forSubframe(), widget.forSubframe());
 
 } // namespace blink
 
 #endif