This adds in the ability for Chrome to generate windows with snapshots of all...

chrome/browser/renderer_host/render_widget_host.cc

Index: chrome/browser/renderer_host/render_widget_host.cc
===================================================================
--- chrome/browser/renderer_host/render_widget_host.cc	(revision 45523)
+++ chrome/browser/renderer_host/render_widget_host.cc	(working copy)
@@ -127,6 +127,7 @@
     IPC_MESSAGE_HANDLER(ViewHostMsg_RenderViewGone, OnMsgRenderViewGone)
     IPC_MESSAGE_HANDLER(ViewHostMsg_Close, OnMsgClose)
     IPC_MESSAGE_HANDLER(ViewHostMsg_RequestMove, OnMsgRequestMove)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_PaintAtSize_ACK, OnMsgPaintAtSizeAck)
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateRect, OnMsgUpdateRect)
     IPC_MESSAGE_HANDLER(ViewHostMsg_CreateVideo, OnMsgCreateVideo)
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateVideo, OnMsgUpdateVideo)
@@ -280,6 +281,14 @@
   view_->SetIsLoading(is_loading);
 }
 
+void RenderWidgetHost::PaintAtSize(TransportDIB::Handle dib_handle,
+                                   const gfx::Size& size) {
+  // Ask the renderer to create a bitmap regardless of whether it's
+  // hidden, being resized, redrawn, etc., and to scale it by the
+  // scale factor given.
+  Send(new ViewMsg_PaintAtSize(routing_id_, dib_handle, size));
+}
+
 BackingStore* RenderWidgetHost::GetBackingStore(bool force_create) {
   // We should not be asked to paint while we are hidden.  If we are hidden,
   // then it means that our consumer failed to call WasRestored. If we're not
@@ -676,6 +685,13 @@
   }
 }
 
+void RenderWidgetHost::OnMsgPaintAtSizeAck(
+    const TransportDIB::Handle& dib_handle, const gfx::Size& size) {
+  if (painting_observer_) {
+    painting_observer_->WidgetDidReceivePaintAtSizeAck(this, dib_handle, size);
+  }
+}
+
 void RenderWidgetHost::OnMsgUpdateRect(
     const ViewHostMsg_UpdateRect_Params& params) {
   TimeTicks paint_start = TimeTicks::Now();