Plumb an overscroll callback form the compositor to the Android UI thread.

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/process.h"
 #include "base/shared_memory.h"
 #include "base/string16.h"
@@ skipping 678 matching lines @@
   // to a view and are only updated by the renderer after this initial value.
   IPC_STRUCT_MEMBER(int32, next_page_id)
 
   // The properties of the screen associated with the view.
   IPC_STRUCT_MEMBER(WebKit::WebScreenInfo, screen_info)
 
   // The accessibility mode of the renderer.
   IPC_STRUCT_MEMBER(AccessibilityMode, accessibility_mode)
 IPC_STRUCT_END()
 
+IPC_STRUCT_BEGIN(ViewHostMsg_UpdateFrameInfo_Params)

[aelias_OOO_until_Jul13, 2013/01/30 18:02:48]

ViewHostMsg_UpdateFrameInfo is going to get deleted after
--enable-compositor-frame-message is set, so I recommend not doing this.  Just
leave them in separate values in the browser process calls and don't touch
UpdateFrameInfo in the renderer.

+  IPC_STRUCT_MEMBER(gfx::Vector2d, scroll_offset)
+  IPC_STRUCT_MEMBER(gfx::Vector2d, unused_scroll_delta)
+  IPC_STRUCT_MEMBER(float, page_scale_factor)
+  IPC_STRUCT_MEMBER(float, min_page_scale_factor)
+  IPC_STRUCT_MEMBER(float, max_page_scale_factor)
+  IPC_STRUCT_MEMBER(gfx::Size, content_size)
+IPC_STRUCT_END()
+
 // Messages sent from the browser to the renderer.
 
 // Set the top-level frame to the provided name.
 IPC_MESSAGE_ROUTED1(ViewMsg_SetName,
                     std::string /* frame_name */)
 
 // Sent to the RenderView when a new tab is swapped into an existing
 // tab and the histories need to be merged. The existing tab has a history of
 // |merged_history_length| which precedes the history of the new tab. All
 // page_ids >= |minimum_page_id| in the new tab are appended to the history.
@@ skipping 601 matching lines @@
 // Tells the renderer to try to revert to the zoom level we were at before
 // ViewMsg_ScrollFocusedEditableNodeIntoView was called.
 IPC_MESSAGE_ROUTED0(ViewMsg_UndoScrollFocusedEditableNodeIntoView)
 
 // Message sent when the renderer changed the background color for the view.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_DidChangeBodyBackgroundColor,
                     uint32  /* bg_color */)
 
 // Information about current document scroll, scale and size. Sent on a
 // best-effort basis.
-IPC_MESSAGE_ROUTED5(ViewHostMsg_UpdateFrameInfo,
-                    gfx::Vector2d /* scroll_offset */,
-                    float /* page_scale_factor */,
-                    float /* min_page_scale_factor */,
-                    float /* max_page_scale_factor */,
-                    gfx::Size /* content_size */)
+IPC_MESSAGE_ROUTED1(ViewHostMsg_UpdateFrameInfo,
+                    ViewHostMsg_UpdateFrameInfo_Params)
 
 #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 */)
@@ skipping 1042 matching lines @@
 // cached by the OS. Please see RenderMessageFilter::OnPreCacheFontCharacters
 // for details.
 IPC_SYNC_MESSAGE_CONTROL2_0(ViewHostMsg_PreCacheFontCharacters,
                             LOGFONT /* font_data */,
                             string16 /* characters */)
 #endif
 
 // Notifies the browser that the frame with the given id was detached.
 IPC_MESSAGE_ROUTED1(ViewHostMsg_FrameDetached,
                     int64 /* frame_id */)