GuestView: Move lifetime management out of content

content/public/browser/browser_plugin_guest_delegate.h

Index: content/public/browser/browser_plugin_guest_delegate.h
diff --git a/content/public/browser/browser_plugin_guest_delegate.h b/content/public/browser/browser_plugin_guest_delegate.h
index 0b7372f52bbc73f5647d23485463f541ecda0247..21e115a203044853e87ac3bc540c1544361ed191 100644
--- a/content/public/browser/browser_plugin_guest_delegate.h
+++ b/content/public/browser/browser_plugin_guest_delegate.h
@@ -57,10 +57,6 @@ class CONTENT_EXPORT BrowserPluginGuestDelegate {
       bool last_unlocked_by_target,
       const base::Callback<void(bool)>& callback) {}
 
-  // Requests that the delegate destroy itself along with its associated
-  // WebContents.
-  virtual void Destroy() {}
-
   // Registers a |callback| with the delegate that the delegate would call when
   // it is about to be destroyed.
   typedef base::Callback<void()> DestructionCallback;