Get FileSelect dialog work on athena

athena/content/app_activity.cc

Index: athena/content/app_activity.cc
diff --git a/athena/content/app_activity.cc b/athena/content/app_activity.cc
index 4315df3d8c39de83d45c63ccef96ab0058a1fea8..885edba95d9f55ac41bc6627e54b3282c0c905c4 100644
--- a/athena/content/app_activity.cc
+++ b/athena/content/app_activity.cc
@@ -96,6 +96,10 @@ aura::Window* AppActivity::GetWindow() {
   return !web_view_ ? NULL : web_view_->GetWidget()->GetNativeWindow();
 }
 
+content::WebContents* AppActivity::GetWebContents() {
+  return !web_view_ ? NULL : web_view_->GetWebContents();
+}
+
 void AppActivity::Init() {
   DCHECK(app_activity_registry_);
   Activity* app_proxy = app_activity_registry_->unloaded_activity_proxy();