Relanding this as the previous attempt failed due to build errors.

webkit/glue/weburlrequest_extradata_impl.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 WEBKIT_GLUE_WEBURLREQUEST_EXTRADATA_IMPL_H_
 #define WEBKIT_GLUE_WEBURLREQUEST_EXTRADATA_IMPL_H_
 
 #include "base/compiler_specific.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebReferrerPolicy.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebString.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebURLRequest.h"
-#include "webkit/glue/webkit_glue_export.h"
 
 namespace webkit_glue {
 
 // Base class for Chrome's implementation of the "extra data" stored in each
 // ResourceRequest.
-class WEBKIT_GLUE_EXPORT WebURLRequestExtraDataImpl :
-    NON_EXPORTED_BASE(public WebKit::WebURLRequest::ExtraData) {
+class WebURLRequestExtraDataImpl
+    : NON_EXPORTED_BASE(public WebKit::WebURLRequest::ExtraData) {

[jamesr, 2013/05/15 20:42:47]

I don't think you should need the NON_EXPORTED_BASE since the derived class
isn't exported

[ananta, 2013/05/15 20:53:34]

Done.

  public:
   // |custom_user_agent| is used to communicate an overriding custom user agent
   // to |RenderViewImpl::willSendRequest()|; set to a null string to indicate no
   // override and an empty string to indicate that there should be no user
   // agent. This needs to be here, instead of content's |RequestExtraData| since
   // ppb_url_request_info_impl.cc needs to be able to set it.
   explicit WebURLRequestExtraDataImpl(
       WebKit::WebReferrerPolicy referrer_policy,
       const WebKit::WebString& custom_user_agent);
   virtual ~WebURLRequestExtraDataImpl();
 
   WebKit::WebReferrerPolicy referrer_policy() const { return referrer_policy_; }
   const WebKit::WebString& custom_user_agent() const {
     return custom_user_agent_;
   }
 
  private:
   WebKit::WebReferrerPolicy referrer_policy_;
   WebKit::WebString custom_user_agent_;
 
   DISALLOW_COPY_AND_ASSIGN(WebURLRequestExtraDataImpl);
 };
 
 }  // namespace webkit_glue
 
 #endif  // WEBKIT_GLUE_WEBURLREQUEST_EXTRADATA_IMPL_H_