Bring up of ImageService.

components/enhanced_bookmarks/bookmark_image_service.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 COMPONENTS_ENHANCED_BOOKMARKS_BOOKMARK_IMAGE_SERVICE_H_
+#define COMPONENTS_ENHANCED_BOOKMARKS_BOOKMARK_IMAGE_SERVICE_H_
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "components/bookmarks/browser/bookmark_model_observer.h"
+#include "components/enhanced_bookmarks/image_store.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "net/url_request/url_request.h"
+#include "url/gurl.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+class BookmarkNode;
+
+namespace enhanced_bookmarks {
+
+// The BookmarkImageService stores salient images for bookmarks.
+class BookmarkImageService : public KeyedService,
+                             public BookmarkModelObserver,
+                             public base::NonThreadSafe {
+ public:
+  explicit BookmarkImageService(const base::FilePath& path,
+                                BookmarkModel* bookmark_model,
+                                scoped_refptr<base::SequencedWorkerPool> pool);
+  BookmarkImageService(scoped_ptr<ImageStore> store,
+                       BookmarkModel* bookmark_model,
+                       scoped_refptr<base::SequencedWorkerPool> pool);
+
+  virtual ~BookmarkImageService();
+
+  typedef base::Callback<void(const gfx::Image&, const GURL& url)> Callback;
+
+  // Returns a salient image for a URL. This may trigger a network request for
+  // the image if the image was not retrieved before and if a bookmark node has
+  // a URL for this salient image available.  The image (which may be empty) is
+  // sent via the callback. The callback may be called synchronously if it is
+  // possible. The callback is always triggered on the main thread.
+  void SalientImageForUrl(const GURL& page_url, Callback callback);
+
+  // BookmarkModelObserver methods.
+  virtual void BookmarkNodeRemoved(BookmarkModel* model,
+                                   const BookmarkNode* parent,
+                                   int old_index,
+                                   const BookmarkNode* node,
+                                   const std::set<GURL>& removed_urls) OVERRIDE;
+  virtual void BookmarkModelLoaded(BookmarkModel* model,
+                                   bool ids_reassigned) OVERRIDE;
+  virtual void BookmarkNodeMoved(BookmarkModel* model,
+                                 const BookmarkNode* old_parent,
+                                 int old_index,
+                                 const BookmarkNode* new_parent,
+                                 int new_index) OVERRIDE;
+  virtual void BookmarkNodeAdded(BookmarkModel* model,
+                                 const BookmarkNode* parent,
+                                 int index) OVERRIDE;
+  virtual void OnWillChangeBookmarkNode(BookmarkModel* model,
+                                        const BookmarkNode* node) OVERRIDE;
+  virtual void BookmarkNodeChanged(BookmarkModel* model,
+                                   const BookmarkNode* node) OVERRIDE;
+  virtual void BookmarkNodeFaviconChanged(BookmarkModel* model,
+                                          const BookmarkNode* node) OVERRIDE;
+  virtual void BookmarkNodeChildrenReordered(BookmarkModel* model,
+                                             const BookmarkNode* node) OVERRIDE;
+  virtual void BookmarkAllUserNodesRemoved(
+      BookmarkModel* model,
+      const std::set<GURL>& removed_urls) OVERRIDE;
+
+ protected:
+  // Returns true if the image for the page_url is currently being fetched.
+  bool IsPageUrlInProgress(const GURL& page_url);
+
+  // Once an image has been retrieved, store the image and notify all the
+  // consumers that were waiting on it.
+  void ProcessNewImage(const GURL& page_url,
+                       bool update_bookmarks,
+                       const gfx::Image& image,
+                       const GURL& image_url);
+
+  // Sets a new image for a bookmark. If the given page_url is bookmarked and
+  // the image is retrieved from the image_url, then the image is locally
+  // stored. If update_bookmark is true the URL is also added to the bookmark.
+  // This is the only method subclass needs to implement.
+  virtual void RetrieveSalientImage(
+      const GURL& page_url,
+      const GURL& image_url,
+      const std::string& referrer,
+      net::URLRequest::ReferrerPolicy referrer_policy,
+      bool update_bookmark) = 0;
+
+  // Retrieves a salient image for a given page_url by downloading the image in
+  // one of the bookmark.
+  virtual void RetrieveSalientImageForPageUrl(const GURL& page_url);
+
+  // PageUrls currently in the progress of being retrieved.
+  std::set<GURL> in_progress_page_urls_;
+
+  // Cached pointer to the bookmarks model.
+  BookmarkModel* bookmark_model_;  // weak
+
+ private:
+  // Same as SalientImageForUrl(const GURL&, Callback) but can prevent the
+  // network request if fetch_from_bookmark is false.
+  void SalientImageForUrl(const GURL& page_url,
+                          bool fetch_from_bookmark,
+                          Callback stack_callback);
+
+  // Processes the requests that have been waiting on an image.
+  void ProcessRequests(const GURL& page_url,
+                       const gfx::Image& image,
+                       const GURL& image_url);
+
+  // Once an image is retrieved this method updates the store with it.
+  void StoreImage(const gfx::Image& image,
+                  const GURL& image_url,
+                  const GURL& page_url);
+
+  // Called when retrieving an image from the image store fails, to trigger
+  // retrieving the image from the url stored in the bookmark (if any).
+  void FetchCallback(const GURL& page_url,
+                     Callback original_callback,
+                     const gfx::Image& image,
+                     const GURL& image_url);
+
+  // Remove the image stored for this bookmark (if it exists). Called when a
+  // bookmark is deleted.
+  void RemoveImageForUrl(const GURL& url);
+
+  // Moves an image from one url to another.
+  void ChangeImageURL(const GURL& from, const GURL& to);
+
+  // Removes all the entries in the image service.
+  void ClearAll();
+
+  // The image store can only be accessed from the blocking pool.
+  // RetrieveImageFromStore starts a request to retrieve the image and returns
+  // the result via a callback. RetrieveImageFromStore must be called on the
+  // main thread and the callback will be called on the main thread as well. The
+  // callback will always be called. The returned image is nil if the image is
+  // not present in the store.
+  void RetrieveImageFromStore(const GURL& page_url,
+                              BookmarkImageService::Callback callback);
+
+  // Maps a pageUrl to an image.
+  scoped_ptr<ImageStore> store_;
+
+  // All the callbacks waiting for a particular image.
+  std::map<const GURL, std::vector<Callback> > callbacks_;
+
+  // When a bookmark is changed, two messages are received on the
+  // bookmarkModelObserver, one with the old state, one with the new. The url
+  // before the change is saved in this instance variable.
+  GURL previous_url_;
+
+  // The worker pool to enqueue the store requests onto.
+  scoped_refptr<base::SequencedWorkerPool> pool_;
+  DISALLOW_COPY_AND_ASSIGN(BookmarkImageService);
+};
+
+}  // namespace enhanced_bookmarks
+
+#endif  // COMPONENTS_ENHANCED_BOOKMARKS_BOOKMARK_IMAGE_SERVICE_H_