Plugs in the new thumbnailing algorithm to ThumbnailTabHelper.

chrome/browser/thumbnails/thumbnailing_algorithm.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 CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_
 #define CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_
 
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/thumbnails/thumbnailing_context.h"
 #include "ui/gfx/rect.h"
@@ skipping 23 matching lines @@
                                        gfx::Size* target_size) const = 0;
 
   // Invoked to produce a thumbnail image from a |bitmap| extracted by the
   // callee from source canvas according to instructions provided by a call
   // to GetCanvasCopyInfo.
   // Note that ProcessBitmap must be able to handle bitmaps which might have not
   // been processed (scalled/cropped) as requested. |context| gives additional
   // information on the source, including if and how it was clipped.
   // The function shall invoke |callback| once done, passing in fully populated
   // |context| along with resulting thumbnail bitmap.
-  virtual void ProcessBitmap(ThumbnailingContext* context,
+  virtual void ProcessBitmap(scoped_refptr<ThumbnailingContext> context,
                              const ConsumerCallback& callback,
                              const SkBitmap& bitmap) = 0;
 
  protected:
   virtual ~ThumbnailingAlgorithm() {}
   friend class base::RefCountedThreadSafe<ThumbnailingAlgorithm>;
 };
 
 }
 
 #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAILING_ALGORITHM_H_