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

content/child/npapi/webplugin.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_CHILD_NPAPI_WEBPLUGIN_H_
 #define CONTENT_CHILD_NPAPI_WEBPLUGIN_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 53 matching lines @@
   virtual bool FindProxyForUrl(const GURL& url, std::string* proxy_list) = 0;
 
   // Cookies
   virtual void SetCookie(const GURL& url,
                          const GURL& first_party_for_cookies,
                          const std::string& cookie) = 0;
   virtual std::string GetCookies(const GURL& url,
                                  const GURL& first_party_for_cookies) = 0;
 
   // Handles GetURL/GetURLNotify/PostURL/PostURLNotify requests initiated
-  // by plugins.  If the plugin wants notification of the result, notify_id will
-  // be non-zero.
+  // by plugins.
   virtual 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) = 0;
 
   // Cancels document load.
   virtual void CancelDocumentLoad() = 0;
 
   // Initiates a HTTP range request for an existing stream.
   virtual void InitiateHTTPRangeRequest(const char* url,
                                         const char* range_info,
                                         int range_request_id) = 0;
@@ skipping 47 matching lines @@
   virtual void AcceleratedPluginAllocatedIOSurface(int32 width,
                                                    int32 height,
                                                    uint32 surface_id) = 0;
   virtual void AcceleratedPluginSwappedIOSurface() = 0;
 #endif
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_NPAPI_WEBPLUGIN_H_