Make Page Visibility API work when the browser window is visible or not

content/browser/frame_host/render_widget_host_view_child_frame.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/common/content_export.h"
@@ skipping 28 matching lines @@
   // RenderWidgetHostView implementation.
   void InitAsChild(gfx::NativeView parent_view) override;
   RenderWidgetHost* GetRenderWidgetHost() const override;
   void SetSize(const gfx::Size& size) override;
   void SetBounds(const gfx::Rect& rect) override;
   void Focus() override;
   bool HasFocus() const override;
   bool IsSurfaceAvailableForCopy() const override;
   void Show() override;
   void Hide() override;
+  void Hide(bool content_visible) override;
   bool IsShowing() override;
   gfx::Rect GetViewBounds() const override;
   gfx::Vector2dF GetLastScrollOffset() const override;
   gfx::NativeView GetNativeView() const override;
   gfx::NativeViewId GetNativeViewId() const override;
   gfx::NativeViewAccessible GetNativeViewAccessible() override;
   void SetBackgroundColor(SkColor color) override;
   gfx::Size GetPhysicalBackingSize() const override;
 
   // RenderWidgetHostViewBase implementation.
@@ skipping 89 matching lines @@
   // sent through it are routed to the embedding renderer process.
   CrossProcessFrameConnector* frame_connector_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewChildFrame);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_WIDGET_HOST_VIEW_CHILD_FRAME_H_