Change panels to be able to turn off autoresize.

content/public/browser/render_view_host_delegate.h

Index: content/public/browser/render_view_host_delegate.h
diff --git a/content/public/browser/render_view_host_delegate.h b/content/public/browser/render_view_host_delegate.h
index 9d8d337d7c698aa0576c61edce15b2ad96da1ede..bc7342d3fc4ce72fa4bcf2642dab6b2256eb9f36 100644
--- a/content/public/browser/render_view_host_delegate.h
+++ b/content/public/browser/render_view_host_delegate.h
@@ -386,6 +386,9 @@ class CONTENT_EXPORT RenderViewHostDelegate : public IPC::Channel::Listener {
   // The contents' preferred size changed.
   virtual void UpdatePreferredSize(const gfx::Size& pref_size) {}
 
+  // The contents auto-resized and the container should match it.
+  virtual void ResizeDueToAutoResize(const gfx::Size& new_size) {}
+
   // Notification message from HTML UI.
   virtual void WebUISend(RenderViewHost* render_view_host,
                          const GURL& source_url,