Remove PluginLoadObserver and related logic, it was only used for NPAPI.

content/plugin/webplugin_proxy.h

 // Copyright (c) 2012 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_PLUGIN_WEBPLUGIN_PROXY_H_
 #define CONTENT_PLUGIN_WEBPLUGIN_PROXY_H_
 
 #include <string>
 
 #include "base/containers/hash_tables.h"
@@ skipping 53 matching lines @@
   void SetCookie(const GURL& url,
                  const GURL& first_party_for_cookies,
                  const std::string& cookie) override;
   std::string GetCookies(const GURL& url,
                          const GURL& first_party_for_cookies) override;
   void HandleURLRequest(const char* url,
                         const char* method,
                         const char* target,
                         const char* buf,
                         unsigned int len,
-                        int notify_id,
                         bool popups_allowed,
                         bool notify_redirects) override;
   void UpdateGeometry(const gfx::Rect& window_rect,
                       const gfx::Rect& clip_rect,
                       const TransportDIB::Handle& windowless_buffer0,
                       const TransportDIB::Handle& windowless_buffer1,
                       int windowless_buffer_index);
   void CancelDocumentLoad() override;
   void InitiateHTTPRangeRequest(const char* url,
                                 const char* range_info,
@@ skipping 126 matching lines @@
 
   // Contains the routing id of the host render view.
   int host_render_view_routing_id_;
 
   base::WeakPtrFactory<WebPluginProxy> weak_factory_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PLUGIN_WEBPLUGIN_PROXY_H_