Implement <appview>

chrome/browser/extensions/api/guest_view/guest_view_internal_api.h

Index: chrome/browser/extensions/api/guest_view/guest_view_internal_api.h
diff --git a/chrome/browser/extensions/api/guest_view/guest_view_internal_api.h b/chrome/browser/extensions/api/guest_view/guest_view_internal_api.h
index aca245916e46162aa50d670a171cddfbf7fb632e..8ae38b4609d22ae0882e947e74e46370259cc5ec 100644
--- a/chrome/browser/extensions/api/guest_view/guest_view_internal_api.h
+++ b/chrome/browser/extensions/api/guest_view/guest_view_internal_api.h
@@ -7,6 +7,10 @@
 
 #include "extensions/browser/extension_function.h"
 
+namespace content {
+class WebContents;
+}  // namespace content
+
 namespace extensions {
 
 class GuestViewInternalCreateGuestFunction : public AsyncExtensionFunction {
@@ -21,6 +25,7 @@ class GuestViewInternalCreateGuestFunction : public AsyncExtensionFunction {
 
  private:
   void CreateGuestCallback(content::WebContents* guest_web_contents);
+
   DISALLOW_COPY_AND_ASSIGN(GuestViewInternalCreateGuestFunction);
 };