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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_
      6 #define CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_
      7 
      8 #include "components/history/core/common/thumbnail_score.h"
      9 #include "components/keyed_service/content/refcounted_browser_context_keyed_service.h"
     10 #include "ui/gfx/image/image.h"
     11 
     12 class GURL;
     13 
     14 namespace base {
     15 class RefCountedMemory;
     16 }
     17 
     18 namespace thumbnails {
     19 
     20 class ThumbnailingAlgorithm;
     21 struct ThumbnailingContext;
     22 
     23 // An interface abstracting access to thumbnails. Intended as a temporary
     24 // bridge facilitating switch from TopSites as the thumbnail source to a more
     25 // robust way of handling these artefacts.
     26 class ThumbnailService : public RefcountedBrowserContextKeyedService {
     27  public:
     28   // Sets the given thumbnail for the given URL. Returns true if the thumbnail
     29   // was updated. False means either the URL wasn't known to us, or we felt
     30   // that our current thumbnail was superior to the given one.
     31   virtual bool SetPageThumbnail(const ThumbnailingContext& context,
     32                                 const gfx::Image& thumbnail) = 0;
     33 
     34   // Returns the ThumbnailingAlgorithm used for processing thumbnails.
     35   // It is always a new instance, the caller owns it. It will encapsulate the
     36   // process of creating a thumbnail from tab contents. The lifetime of these
     37   // instances is limited to the act of processing a single tab image. They
     38   // are permitted to hold the state of such process.
     39   virtual ThumbnailingAlgorithm* GetThumbnailingAlgorithm() const = 0;
     40 
     41   // Gets a thumbnail for a given page. Returns true iff we have the thumbnail.
     42   // This may be invoked on any thread.
     43   // If an exact thumbnail URL match fails, |prefix_match| specifies whether or
     44   // not to try harder by matching the query thumbnail URL as URL prefix (as
     45   // defined by UrlIsPrefix()).
     46   // As this method may be invoked on any thread the ref count needs to be
     47   // incremented before this method returns, so this takes a scoped_refptr*.
     48   virtual bool GetPageThumbnail(
     49       const GURL& url,
     50       bool prefix_match,
     51       scoped_refptr<base::RefCountedMemory>* bytes) = 0;
     52 
     53   // Add or updates a |url| for which we should force the capture of a thumbnail
     54   // next time it's visited.
     55   virtual void AddForcedURL(const GURL& url) = 0;
     56 
     57   // Returns true if the page thumbnail should be updated.
     58   virtual bool ShouldAcquirePageThumbnail(const GURL& url) = 0;
     59 
     60  protected:
     61   virtual ~ThumbnailService() {}
     62 };
     63 
     64 }  // namespace thumbnails
     65 
     66 #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_H_
     67