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

content/child/npapi/webplugin_resource_client.h

 // Copyright (c) 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_CHILD_NPAPI_WEBPLUGIN_RESOURCE_CLIENT_H_
 #define CONTENT_CHILD_NPAPI_WEBPLUGIN_RESOURCE_CLIENT_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 14 matching lines @@
                                   const std::string& headers,
                                   uint32 expected_length,
                                   uint32 last_modified,
                                   bool request_is_seekable) = 0;
   virtual void DidReceiveData(const char* buffer, int length,
                               int data_offset) = 0;
   // The resource ids passed here ensures that data for range requests
   // is cleared. This applies for seekable streams.
   virtual void DidFinishLoading(unsigned long resource_id) = 0;
   virtual void DidFail(unsigned long resource_id) = 0;
-  virtual bool IsMultiByteResponseExpected() = 0;
   virtual int ResourceId() = 0;
   // Tells this object that it will get responses from multiple resources.
   // This is necessary since the plugin process uses a single instance of
   // PluginStreamUrl object for multiple range requests.
   virtual void AddRangeRequestResourceId(unsigned long resource_id) { }
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_NPAPI_WEBPLUGIN_RESOURCE_CLIENT_H_