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

content/plugin/webplugin_proxy.cc

 // 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.
 
 #include "content/plugin/webplugin_proxy.h"
 
 #include "build/build_config.h"
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ skipping 257 matching lines @@
                                        WebPluginResourceClient* client) {
   DCHECK(resource_clients_.find(resource_id) == resource_clients_.end());
   resource_clients_[resource_id] = client;
 }
 
 void WebPluginProxy::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) {
   if (!target && base::EqualsCaseInsensitiveASCII(method, "GET")) {
     // Please refer to https://bugzilla.mozilla.org/show_bug.cgi?id=366082
     // for more details on this.
     if (delegate_->GetQuirks() &
         WebPluginDelegateImpl::PLUGIN_QUIRK_BLOCK_NONSTANDARD_GETURL_REQUESTS) {
       GURL request_url(url);
       if (!request_url.SchemeIs(url::kHttpScheme) &&
           !request_url.SchemeIs(url::kHttpsScheme) &&
           !request_url.SchemeIs(url::kFtpScheme)) {
         return;
       }
     }
   }
 
   PluginHostMsg_URLRequest_Params params;
   params.url = url;
   params.method = method;
   if (target)
     params.target = std::string(target);
 
   if (len) {
     params.buffer.resize(len);
     memcpy(&params.buffer.front(), buf, len);
   }
 
-  params.notify_id = notify_id;
   params.popups_allowed = popups_allowed;
   params.notify_redirects = notify_redirects;
 
   Send(new PluginHostMsg_URLRequest(route_id_, params));
 }
 
 void WebPluginProxy::Paint(const gfx::Rect& rect) {
 #if defined(OS_MACOSX)
   if (!windowless_context())
     return;
@@ skipping 287 matching lines @@
   int input_type;
   gfx::Rect caret_rect;
   if (!delegate_->GetIMEStatus(&input_type, &caret_rect))
     return;
 
   Send(new PluginHostMsg_NotifyIMEStatus(route_id_, input_type, caret_rect));
 }
 #endif
 
 }  // namespace content