[Suggestions] Adding a Thumbnail Manager for the Suggestions Service

chrome/browser/search/suggestions/thumbnail_manager.h

+// Copyright 2014 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_SEARCH_SUGGESTIONS_THUMBNAIL_MANAGER_H_
+#define CHROME_BROWSER_SEARCH_SUGGESTIONS_THUMBNAIL_MANAGER_H_
+
+#include <map>
+#include <utility>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "chrome/browser/bitmap_fetcher.h"
+#include "ui/gfx/image/image_skia.h"
+#include "url/gurl.h"
+
+class Profile;
+
+namespace suggestions {
+
+typedef base::Callback<void(const GURL&, const SkBitmap*)>
+    BitmapResponseCallback;
+
+class SuggestionsProfile;
+
+// A class used to fetch server thumbnails asynchronously.
+class ThumbnailManager : public chrome::BitmapFetcherDelegate {
+ public:
+  explicit ThumbnailManager(Profile* profile);
+  virtual ~ThumbnailManager();
+
+  // Initializes the |thumbnail_map_| with the proper mapping from website URL
+  // to thumbnail URL.
+  void InitializeThumbnailMap(const SuggestionsProfile& suggestions);
+
+  // Retrieves stored thumbnail for website |url| asynchronously. Calls
+  // |callback| with Bitmap pointer if found, and NULL otherwise. Should be
+  // called from the UI thread.
+  void GetPageThumbnail(
+      const GURL& url,
+      base::Callback<void(const GURL&, const SkBitmap*)> callback);

[Jered, 2014/05/23 21:25:00]

This doesn't use the typedef above?

[huangs, 2014/05/23 22:34:26]

We decided to not use

typedef BitmapResponseCallback;

because it breaks encapsulation, i.e., caller of SuggestionsService should not
know about ThumbnailManager.  So lines 22-24 should be deleted.

[Mathieu, 2014/05/23 22:40:25]

Oops I meant to remove the typedef. I want to avoid callers relying on this file
to be included (even indirectly) to be informed of the callback type.

+
+

[Jered, 2014/05/23 21:25:00]

nit: omit this extra blank line

[Mathieu, 2014/05/23 22:40:25]

Done.

+ private:
+  FRIEND_TEST_ALL_PREFIXES(ThumbnailManagerTest, InitializeThumbnailMapTest);
+  FRIEND_TEST_ALL_PREFIXES(ThumbnailManagerBrowserTest, FetchThumbnails);
+  FRIEND_TEST_ALL_PREFIXES(ThumbnailManagerBrowserTest, FetchThumbnailsInvalid);
+  FRIEND_TEST_ALL_PREFIXES(ThumbnailManagerBrowserTest,
+                           FetchThumbnailsMultiple);
+
+  typedef std::vector<base::Callback<void(const GURL&, const SkBitmap*)> >
+      CallbackVector;
+
+  // State related to a thumbnail fetch (associated website url, fetcher,
+  // pending callbacks).
+  struct ThumbnailRequest {
+    ThumbnailRequest();
+    ~ThumbnailRequest();
+
+    GURL url;
+    chrome::BitmapFetcher* fetcher;
+    // Queue for pending callbacks, which may accumulate while the request is in
+    // flight.
+    CallbackVector callbacks;
+  };
+
+  typedef std::map<const GURL, ThumbnailRequest> ThumbnailRequestMap;
+
+  // Inherited from BitmapFetcherDelegate. Runs on the UI thread.
+  virtual void OnFetchComplete(const GURL thumbnail_url,
+                               const SkBitmap* bitmap) OVERRIDE;
+
+  // Looks up thumbnail for |url|. If found, writes the result to
+  // |thumbnail_url| and returns true. Otherwise just returns false.
+  bool GetThumbnailURL(const GURL& url, GURL* thumbnail_url);
+
+  // Used for substituting the request context during testing.
+  void set_request_context(net::URLRequestContextGetter* context) {
+    url_request_context_ = context;
+  }
+
+  // Map from URL to thumbnail URL. Should be kept up to date when a new
+  // SuggestionsProfile is available.
+  std::map<GURL, GURL> thumbnail_map_;
+
+  // Map from each thumbnail URL to the request information (associated website
+  // url, fetcher, pending callbacks).
+  ThumbnailRequestMap pending_requests_;
+
+  net::URLRequestContextGetter* url_request_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThumbnailManager);
+};
+
+}  // namespace suggestions
+
+#endif  // CHROME_BROWSER_SEARCH_SUGGESTIONS_THUMBNAIL_MANAGER_H_