Disable partial swaps for webview guest renderer until we can figure out how to do that properly.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 6e81f97aa1e0935350f3bd82f7e9fbb31aa38852..95966d30767cbb9b740c8739aee9bc062b089640 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -277,6 +277,10 @@ void RenderWidget::SetSwappedOut(bool is_swapped_out) {
     RenderProcess::current()->AddRefProcess();
 }
 
+bool RenderWidget::AllowPartialSwap() const {
+  return true;
+}
+
 bool RenderWidget::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(RenderWidget, message)