Generate thumbnails in the browser process.

chrome/browser/renderer_host/render_view_host.h

Index: chrome/browser/renderer_host/render_view_host.h
diff --git a/chrome/browser/renderer_host/render_view_host.h b/chrome/browser/renderer_host/render_view_host.h
index 5278eff06799502e4d201ccd232a80f5253bb980..eec637e024e8af1ec7e66768420eaacfdbd6660a 100644
--- a/chrome/browser/renderer_host/render_view_host.h
+++ b/chrome/browser/renderer_host/render_view_host.h
@@ -542,6 +542,8 @@ class RenderViewHost : public RenderWidgetHost {
                         int renderer_id,
                         GURL* url);
 
+  const gfx::Size& last_scroll_offset() const { return last_scroll_offset_; }
+
  protected:
   // RenderWidgetHost protected overrides.
   virtual bool PreHandleKeyboardEvent(const NativeWebKeyboardEvent& event,
@@ -703,6 +705,7 @@ class RenderViewHost : public RenderWidgetHost {
   void OnUpdateContentRestrictions(int restrictions);
   void OnPagesReadyForPreview(
       const ViewHostMsg_DidPreviewDocument_Params& params);
+  void OnUpdateScrollOffset(const gfx::Size& size);
 
 #if defined(OS_MACOSX)
   void OnMsgShowPopup(const ViewHostMsg_ShowPopup_Params& params);
@@ -791,6 +794,9 @@ class RenderViewHost : public RenderWidgetHost {
   // The termination status of the last render view that terminated.
   base::TerminationStatus render_view_termination_status_;
 
+  // The last scroll offset of the render view.
+  gfx::Size last_scroll_offset_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderViewHost);
 };