Implement overscroll support for the virtual keyboard.

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 584 matching lines @@
 IPC_MESSAGE_CONTROL0(ViewMsg_TimezoneChange)
 
 // Tells the render view to close.
 IPC_MESSAGE_ROUTED0(ViewMsg_Close)
 
 IPC_STRUCT_BEGIN(ViewMsg_Resize_Params)
   IPC_STRUCT_MEMBER(blink::WebScreenInfo, screen_info)
   IPC_STRUCT_MEMBER(gfx::Size, new_size)
   IPC_STRUCT_MEMBER(gfx::Size, physical_backing_size)
   IPC_STRUCT_MEMBER(float, overdraw_bottom_height)
+  IPC_STRUCT_MEMBER(gfx::Size, visible_viewport_size)
   IPC_STRUCT_MEMBER(gfx::Rect, resizer_rect)
   IPC_STRUCT_MEMBER(bool, is_fullscreen)
 IPC_STRUCT_END()
 
 // Tells the render view to change its size.  A ViewHostMsg_UpdateRect message
 // is generated in response provided new_size is not empty and not equal to
 // the view's current size.  The generated ViewHostMsg_UpdateRect message will
 // have the IS_RESIZE_ACK flag set. It also receives the resizer rect so that
 // we don't have to fetch it every time WebKit asks for it.
 IPC_MESSAGE_ROUTED1(ViewMsg_Resize,
@@ skipping 1204 matching lines @@
 // synchronously (see crbug.com/120597). This IPC message sends the character
 // bounds after every composition change to always have correct bound info.
 IPC_MESSAGE_ROUTED2(ViewHostMsg_ImeCompositionRangeChanged,
                     gfx::Range /* composition range */,
                     std::vector<gfx::Rect> /* character bounds */)
 #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.