GuestViews should be able to specify task manager entries

extensions/browser/guest_view/web_view/web_view_guest_delegate.h

Index: extensions/browser/guest_view/web_view/web_view_guest_delegate.h
diff --git a/extensions/browser/guest_view/web_view/web_view_guest_delegate.h b/extensions/browser/guest_view/web_view/web_view_guest_delegate.h
index d72ae0ee6f5c4a46975d1cd48fd18b3761e2ca0b..6ed07d77ef9d0d0623636cee030ca948928ac186 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest_delegate.h
+++ b/extensions/browser/guest_view/web_view/web_view_guest_delegate.h
@@ -10,12 +10,12 @@
 namespace content {
 class RenderViewHost;
 class WebContents;
-}
+}  // namespace content
 
 namespace extensions {
 
 namespace api {
-namespace web_view_internal{
+namespace web_view_internal {
 
 struct ContextMenuItem;
 
@@ -31,6 +31,9 @@ class WebViewGuestDelegate {
   typedef std::vector<linked_ptr<api::web_view_internal::ContextMenuItem> >
       MenuItemVector;
 
+  // Returns the task prefix for <webview>.
+  virtual int GetTaskPrefix() const = 0;
+
   // Returns the current zoom factor.
   virtual double GetZoom() = 0;