Fix classes that have too many virtuals for inline constructors.

content/browser/frame_host/navigator_delegate.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_DELEGATE_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_DELEGATE_H_
 
 #include "base/strings/string16.h"
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/navigation_controller.h"
@@ skipping 107 matching lines @@
   // navigation, or triggered by history.pushState/replaceState.
   virtual void DidStartLoading(FrameTreeNode* frame_tree_node,
                                bool to_different_document) {}
 
   // A document stopped loading. This corresponds to Blink's notion of the
   // throbber stopping.
   virtual void DidStopLoading() {}
 
   // The load progress was changed.
   virtual void DidChangeLoadProgress() {}
+
+ protected:
+  NavigatorDelegate() = default;
 };
 
 }  // namspace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATOR_DELEGATE_H_