Implementation of device metrics emulation in render view.

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 1631 matching lines @@
 IPC_STRUCT_BEGIN(ViewHostMsg_BeginSmoothScroll_Params)
   IPC_STRUCT_MEMBER(bool, scroll_down)
   IPC_STRUCT_MEMBER(int, pixels_to_scroll)
   IPC_STRUCT_MEMBER(int, mouse_event_x)
   IPC_STRUCT_MEMBER(int, mouse_event_y)
 IPC_STRUCT_END()
 
 IPC_MESSAGE_ROUTED1(ViewHostMsg_BeginSmoothScroll,
                     ViewHostMsg_BeginSmoothScroll_Params /* params */)
 
+// Sent to make host accept image of a certain expected size instead of current
+// view size. This is essential to emulate device metrics, where render widget
+// renders only a part of the hosting view. Empty |size| means that default view
+// size is expected.
+IPC_MESSAGE_ROUTED1(ViewHostMsg_SetExpectedSize,
+                    gfx::Size /* size */)
+
 IPC_MESSAGE_ROUTED0(ViewHostMsg_Focus)
 IPC_MESSAGE_ROUTED0(ViewHostMsg_Blur)
 
 // Message sent from renderer to the browser when focus changes inside the
 // webpage. The parameter says whether the newly focused element needs
 // keyboard input (true for textfields, text areas and content editable divs).
 IPC_MESSAGE_ROUTED1(ViewHostMsg_FocusedNodeChanged,
     bool /* is_editable_node */)
 
 IPC_MESSAGE_ROUTED1(ViewHostMsg_SetCursor,
@@ skipping 707 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,
                     ui::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.