Cleanup: Remove unneeded browser_thread.h includes in content/.

content/browser/streams/stream_handle_impl.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_BROWSER_STREAMS_STREAM_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_STREAMS_STREAM_HANDLE_IMPL_H_
 
 #include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop_proxy.h"
 #include "base/synchronization/lock.h"
 #include "content/public/browser/stream_handle.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace content {
 
 class Stream;
 
 class StreamHandleImpl : public StreamHandle {
  public:
   StreamHandleImpl(const base::WeakPtr<Stream>& stream,
                    const GURL& original_url,
                    const std::string& mime_type);
   virtual ~StreamHandleImpl();
 
  private:
   // StreamHandle overrides
   virtual const GURL& GetURL() OVERRIDE;
   virtual const GURL& GetOriginalURL() OVERRIDE;
   virtual const std::string& GetMimeType() OVERRIDE;
 
   base::WeakPtr<Stream> stream_;
   GURL url_;
   GURL original_url_;
   std::string mime_type_;
   base::MessageLoopProxy* stream_message_loop_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_STREAMS_STREAM_HANDLE_IMPL_H_