Make extensions in the extension shelf render their content to a visible GTK

chrome/browser/gtk/extension_view_gtk.h

Index: chrome/browser/gtk/extension_view_gtk.h
diff --git a/chrome/browser/gtk/extension_view_gtk.h b/chrome/browser/gtk/extension_view_gtk.h
index 61e58fd4fdc2d6ad756844e7970f0f9dfbbb3d49..b569c039bf61c77ecd40580382b7e432619cd432 100644
--- a/chrome/browser/gtk/extension_view_gtk.h
+++ b/chrome/browser/gtk/extension_view_gtk.h
@@ -18,11 +18,17 @@ class ExtensionViewGtk {
 
   gfx::NativeView native_view();
 
+  bool is_toolstrip() const { return is_toolstrip_; }
+  void set_is_toolstrip(bool is_toolstrip) { is_toolstrip_ = is_toolstrip; }
+
  private:
   RenderViewHost* render_view_host() const;
 
   void CreateWidgetHostView();
 
+  // True if the contents are being displayed inside the extension shelf.
+  bool is_toolstrip_;
+
   ExtensionHost* extension_host_;
 
   RenderWidgetHostViewGtk* render_widget_host_view_;