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

content/common/view_messages.h

 // Copyright (c) 2012 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.
 
 // IPC messages for page rendering.
 // Multiply-included message file, hence no include guard.
 
 #include "base/memory/shared_memory.h"
 #include "base/process/process.h"
 #include "base/strings/string16.h"
@@ skipping 957 matching lines @@
 // Sent by the browser when an IME update that requires acknowledgement has been
 // processed on the browser side.
 IPC_MESSAGE_ROUTED0(ViewMsg_ImeEventAck)
 
 // Extracts the data at the given rect, returning it through the
 // ViewHostMsg_SmartClipDataExtracted IPC.
 IPC_MESSAGE_ROUTED1(ViewMsg_ExtractSmartClipData,
                     gfx::Rect /* rect */)
 
 #elif defined(OS_MACOSX)
-// Let the RenderView know its window has changed visibility.
-IPC_MESSAGE_ROUTED1(ViewMsg_SetWindowVisibility,
-                    bool /* visibile */)
-
 // Let the RenderView know its window's frame has changed.
 IPC_MESSAGE_ROUTED2(ViewMsg_WindowFrameChanged,
                     gfx::Rect /* window frame */,
                     gfx::Rect /* content view frame */)
 
 // Message sent from the browser to the renderer when the user starts or stops
 // resizing the view.
 IPC_MESSAGE_ROUTED1(ViewMsg_SetInLiveResize,
                     bool /* enable */)
 
 // Tell the renderer that plugin IME has completed.
 IPC_MESSAGE_ROUTED2(ViewMsg_PluginImeCompositionCompleted,
                     base::string16 /* text */,
                     int /* plugin_id */)
 #endif
 
+// Let the RenderView know its window has changed visibility.
+IPC_MESSAGE_ROUTED1(ViewMsg_SetWindowVisibility,
+                    bool /* visibile */)
+
 // Sent by the browser as a reply to ViewHostMsg_SwapCompositorFrame.
 IPC_MESSAGE_ROUTED2(ViewMsg_SwapCompositorFrameAck,
                     uint32 /* output_surface_id */,
                     cc::CompositorFrameAck /* ack */)
 
 // Sent by browser to tell renderer compositor that some resources that were
 // given to the browser in a swap are not being used anymore.
 IPC_MESSAGE_ROUTED2(ViewMsg_ReclaimCompositorResources,
                     uint32 /* output_surface_id */,
                     cc::CompositorFrameAck /* ack */)
@@ skipping 666 matching lines @@
 // cached by the OS. Please see RenderMessageFilter::OnPreCacheFontCharacters
 // for details.
 IPC_SYNC_MESSAGE_CONTROL2_0(ViewHostMsg_PreCacheFontCharacters,
                             LOGFONT /* font_data */,
                             base::string16 /* characters */)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent ViewMsg, then ifdefs for platform specific ViewMsg, then platform
 // independent ViewHostMsg, then ifdefs for platform specific ViewHostMsg.