Implementing chrome://thumbnails page to view URLs in TopSites and cached thumbnails.

chrome/browser/thumbnails/thumbnail_service.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 CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_
 #define CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_
 
 #include "chrome/common/thumbnail_score.h"
 #include "components/browser_context_keyed_service/refcounted_browser_context_keyed_service.h"
 #include "ui/gfx/image/image.h"
-#include "url/gurl.h"
+
+class GURL;
 
 namespace base {
 class RefCountedMemory;
 }
 
 namespace thumbnails {
 
 class ThumbnailingAlgorithm;
 struct ThumbnailingContext;
 
@@ skipping 11 matching lines @@
   // Returns the ThumbnailingAlgorithm used for processing thumbnails.
   // It is always a new instance, the caller owns it. It will encapsulate the
   // process of creating a thumbnail from tab contents. The lifetime of these
   // instances is limited to the act of processing a single tab image. They
   // are permitted to hold the state of such process.
   virtual ThumbnailingAlgorithm* GetThumbnailingAlgorithm() const = 0;
 
   // Gets a thumbnail for a given page. Returns true iff we have the thumbnail.
   // This may be invoked on any thread.
   // If an exact thumbnail URL match fails, |prefix_match| specifies whether or
-  // not to try harder by matching the query thumbnail URL as URL prefix.
+  // not to try harder by matching the query thumbnail URL as URL prefix (as
+  // defined by UrlIsPrefix()).
   // As this method may be invoked on any thread the ref count needs to be
   // incremented before this method returns, so this takes a scoped_refptr*.
   virtual bool GetPageThumbnail(
       const GURL& url,
       bool prefix_match,
       scoped_refptr<base::RefCountedMemory>* bytes) = 0;
 
   // Returns true if the page thumbnail should be updated.
   virtual bool ShouldAcquirePageThumbnail(const GURL& url) = 0;
 
  protected:
   virtual ~ThumbnailService() {}
 };
 
 }  // namespace thumbnails
 
 #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_