[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 <queue>
+#include <utility>
+
+#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 base class to maintain and fetch server thumbnails asynchronously.

[Jered, 2014/05/23 16:57:48]

Here, explain what you mean by "maintain". Does this mean "cache"? Since this is
a base class, what functionality does it provide by default, and what does it
expect to be customized?

[Mathieu, 2014/05/23 19:21:58]

Reworded. It doesn't cache for now, will add it when it does.

+class ThumbnailManager : public chrome::BitmapFetcherDelegate {
+ public:
+  explicit ThumbnailManager(Profile* profile);
+  virtual ~ThumbnailManager();
+
+  // Initializes the |thumbnail_map_| with the proper mapping from URL to

[Jered, 2014/05/23 16:57:48]

Does "URL" here mean "website URL"?

[Mathieu, 2014/05/23 19:21:58]

Done.

+  // thumbnail URL.
+  void InitializeThumbnailMap(const SuggestionsProfile& suggestions);
+
+  // Retrieves stored thumbnail for website |url| asynchronously. Returns

[Jered, 2014/05/23 16:57:48]

Same comment about "returns" here.

[Mathieu, 2014/05/23 19:21:58]

Done.

+  // thumbnail image as a Bitmap pointer to |callback| if found, and NULL
+  // otherwise. Calls should originate from the UI thread.
+  void GetPageThumbnail(const GURL& url, BitmapResponseCallback callback);
+
+  // Inherited from BitmapFetcherDelegate. Runs on the UI thread.
+  virtual void OnFetchComplete(const GURL thumbnail_url,
+                               const SkBitmap* bitmap) OVERRIDE;
+
+ 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);
+
+  // Contains the information related with a thumbnail fetch (associated website

[Jered, 2014/05/23 16:57:48]

Omit "contains the". information -> state, related with -> related to

[Mathieu, 2014/05/23 19:21:58]

Done.

+  // url, fetcher, pending callbacks).
+  struct Session {

[Jered, 2014/05/23 16:57:48]

"ThumbnailRequest" might be a better name for this struct.

[Mathieu, 2014/05/23 19:21:58]

Done.

+    Session();
+    ~Session();
+
+    GURL url;
+    chrome::BitmapFetcher* fetcher;
+    // Queue for pending callbacks, which may accumulate while the request is in
+    // flight.
+    std::queue<BitmapResponseCallback> callbacks;

[Jered, 2014/05/23 16:57:48]

Use a vector here. You don't really need linked allocation, since you're just
going to walk over these once in order and then delete them all---better to do
that all at once.

[Mathieu, 2014/05/23 19:21:58]

Done.

+  };
+
+  typedef std::map<const GURL, Session> ThumbnailSessionMap;
+
+  // 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 session information (associated website
+  // url, fetcher, pending callbacks).
+  ThumbnailSessionMap session_map_;

[Jered, 2014/05/23 16:57:48]

I'd call this pending_requests_.

[Mathieu, 2014/05/23 19:21:58]

Done.

+
+  net::URLRequestContextGetter* url_request_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThumbnailManager);
+};
+
+}  // namespace suggestions
+
+#endif  // CHROME_BROWSER_SEARCH_SUGGESTIONS_THUMBNAIL_MANAGER_H_