Implement overscroll support for the virtual keyboard.

content/browser/renderer_host/render_widget_host_impl.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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <deque>
 #include <list>
 #include <map>
@@ skipping 743 matching lines @@
   // The current size of the RenderWidget.
   gfx::Size current_size_;
 
   // The size of the view's backing surface in non-DPI-adjusted pixels.
   gfx::Size physical_backing_size_;
 
   // The height of the physical backing surface that is overdrawn opaquely in
   // the browser, for example by an on-screen-keyboard (in DPI-adjusted pixels).
   float overdraw_bottom_height_;
 
+  // The size of the visible viewport, which may be smaller than the view if the
+  // view is partially occluded (e.g. by a virtual keyboard).  The size is in
+  // DPI-adjusted pixels.
+  gfx::Size visible_viewport_size_;
+
   // The size we last sent as requested size to the renderer. |current_size_|
   // is only updated once the resize message has been ack'd. This on the other
   // hand is updated when the resize message is sent. This is very similar to
   // |resize_ack_pending_|, but the latter is not set if the new size has width
   // or height zero, which is why we need this too.
   gfx::Size last_requested_size_;
 
   // The next auto resize to send.
   gfx::Size new_auto_size_;
 
@@ skipping 105 matching lines @@
 #endif
 
   int64 last_input_number_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_