Remove OnThemeChanged and associated unused message

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 642 matching lines @@
 IPC_MESSAGE_ROUTED2(ViewMsg_EnumerateDirectoryResponse,
                     int /* request_id */,
                     std::vector<base::FilePath> /* files_in_directory */)
 
 // Instructs the renderer to close the current page, including running the
 // onunload event handler.
 //
 // Expects a ClosePage_ACK message when finished.
 IPC_MESSAGE_ROUTED0(ViewMsg_ClosePage)
 
-// Notifies the renderer about ui theme changes
-IPC_MESSAGE_ROUTED0(ViewMsg_ThemeChanged)
-
 // Notifies the renderer that a paint is to be generated for the rectangle
 // passed in.
 IPC_MESSAGE_ROUTED1(ViewMsg_Repaint,
                     gfx::Size /* The view size to be repainted */)
 
 // Notification that a move or resize renderer's containing window has
 // started.
 IPC_MESSAGE_ROUTED0(ViewMsg_MoveOrResizeStarted)
 
 IPC_MESSAGE_ROUTED2(ViewMsg_UpdateScreenRects,
@@ skipping 500 matching lines @@
                     int /* y */)
 
 #elif defined(OS_MACOSX)
 // Receives content of a web page as plain text.
 IPC_MESSAGE_ROUTED1(ViewMsg_GetRenderedTextCompleted, std::string)
 #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.