Prioritize smaller favicons over larger ones for tabs, etc. (Take 3)

chrome/browser/favicon/favicon_handler.h

 // Copyright (c) 2011 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_FAVICON_FAVICON_HANDLER_H_
 #define CHROME_BROWSER_FAVICON_FAVICON_HANDLER_H_
 #pragma once
 
 #include <map>
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/cancelable_request.h"
 #include "chrome/browser/favicon/favicon_service.h"
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 #include "chrome/common/favicon_url.h"
 #include "chrome/common/ref_counted_util.h"
 #include "googleurl/src/gurl.h"
 #include "ui/gfx/favicon_size.h"
+#include "ui/gfx/image/image.h"
 
 class FaviconHandlerDelegate;
 class Profile;
 class RefCountedMemory;
 class SkBitmap;
 class TabContents;
 
 namespace content {
 class NavigationEntry;
 }
 
-namespace gfx {
-class Image;
-}
-
 // FaviconHandler works with FaviconTabHelper to fetch the specific type of
 // favicon.
 //
 // FetchFavicon requests the favicon from the favicon service which in turn
 // requests the favicon from the history database. At this point
 // we only know the URL of the page, and not necessarily the url of the
 // favicon. To ensure we handle reloading stale favicons as well as
 // reloading a favicon on page reload we always request the favicon from
 // history regardless of whether the NavigationEntry has a favicon.
 //
@@ skipping 19 matching lines @@
 //   download the favicon.
 // . Otherwise we ask the history database to update the mapping from
 //   page url to favicon url and call us back with the favicon. Remember, it is
 //   possible for the db to already have the favicon, just not the mapping
 //   between page to favicon url. The callback for this is OnFaviconData.
 //
 // OnFaviconData either updates the favicon of the NavigationEntry (if the
 // db knew about the favicon), or requests the renderer to download the
 // favicon.
 //
-// When the renderer downloads the favicon SetFavicon is invoked,
-// at which point we update the favicon of the NavigationEntry and notify
-// the database to save the favicon.
+// When the renderer downloads favicons, it considers the entire list of
+// favicon candidates and chooses the one that best matches the preferred size
+// (or the first one if there is no preferred size). Once the matching favicon
+// has been determined, SetFavicon is called which updates the favicon of the
+// NavigationEntry and notifies the database to save the favicon.
 
 class FaviconHandler {
  public:
   enum Type {
     FAVICON,
     TOUCH,
   };
 
   FaviconHandler(Profile* profile,
                  FaviconHandlerDelegate* delegate,
                  Type icon_type);
   virtual ~FaviconHandler();
 
   // Initiates loading the favicon for the specified url.
   void FetchFavicon(const GURL& url);
 
   // Initiates loading an image from given |image_url|. Returns a download id
   // for caller to track the request. When download completes, |callback| is
   // called with the three params: the download_id, a boolean flag to indicate
   // whether the download succeeds and a SkBitmap as the downloaded image.
   // Note that |image_size| is a hint for images with multiple sizes. The
   // downloaded image is not resized to the given image_size. If 0 is passed,
   // the first frame of the image is returned.
   int DownloadImage(const GURL& image_url,
                     int image_size,
                     history::IconType icon_type,
                     const FaviconTabHelper::ImageDownloadCallback& callback);
 
   // Message Handler.  Must be public, because also called from
-  // PrerenderContents.
+  // PrerenderContents. Collects the |image_urls| list.
   void OnUpdateFaviconURL(int32 page_id,
                           const std::vector<FaviconURL>& candidates);
 
+  // Processes the current image_irls_ entry, requesting the image from the
+  // history / download service.
+  void ProcessCurrentUrl();
+
   void OnDidDownloadFavicon(int id,
                             const GURL& image_url,
                             bool errored,
                             const gfx::Image& image);
 
  protected:
   // These virtual methods make FaviconHandler testable and are overridden by
   // TestFaviconHandler.
 
   // Return the NavigationEntry for the active entry, or NULL if the active
@@ skipping 44 matching lines @@
                     const GURL& image_url,
                     const FaviconTabHelper::ImageDownloadCallback& callback,
                     history::IconType icon_type);
 
     GURL url;
     GURL image_url;
     FaviconTabHelper::ImageDownloadCallback callback;
     history::IconType icon_type;
   };
 
+  struct FaviconCandidate {
+    FaviconCandidate();
+    ~FaviconCandidate();
+
+    FaviconCandidate(const GURL& url,
+                     const GURL& image_url,
+                     const gfx::Image& image,
+                     int bitmap_size,
+                     history::IconType icon_type);
+
+    GURL url;
+    GURL image_url;
+    gfx::Image image;
+    int bitmap_size;
+    history::IconType icon_type;
+  };
+
   // See description above class for details.
   void OnFaviconDataForInitialURL(FaviconService::Handle handle,
                                   history::FaviconData favicon);
 
   // If the favicon has expired, asks the renderer to download the favicon.
   // Otherwise asks history to update the mapping between page url and icon
   // url with a callback to OnFaviconData when done.
   void DownloadFaviconOrAskHistory(const GURL& page_url,
                                    const GURL& icon_url,
                                    history::IconType icon_type);
 
   // See description above class for details.
   void OnFaviconData(FaviconService::Handle handle,
                      history::FaviconData favicon);
 
   // Schedules a download for the specified entry. This adds the request to
   // download_requests_.
   int ScheduleDownload(const GURL& url,
                        const GURL& image_url,
                        int image_size,
                        history::IconType icon_type,
                        const FaviconTabHelper::ImageDownloadCallback& callback);
 
-  // Sets the image data for the favicon. This is invoked asynchronously after
-  // we request the TabContents to download the favicon.
+  // Updates |favicon_candidate_| and returns true if it is an exact match.
+  bool UpdateFaviconCandidate(const GURL& url,
+                              const GURL& image_url,
+                              const gfx::Image& image,
+                              history::IconType icon_type);
+
+  // Sets the image data for the favicon.
   void SetFavicon(const GURL& url,
                   const GURL& icon_url,
                   const gfx::Image& image,
                   history::IconType icon_type);
 
   // Converts the FAVICON's image data to an SkBitmap and sets it on the
   // NavigationEntry.
   // If the TabContents has a delegate, it is notified of the new favicon
   // (INVALIDATE_FAVICON).
   void UpdateFavicon(content::NavigationEntry* entry,
                      scoped_refptr<RefCountedMemory> data);
   void UpdateFavicon(content::NavigationEntry* entry, const gfx::Image* image);
 
   // If the image is not already at its preferred size, scales the image such
-  // that either the width and/or height is 16 pixels wide. Does nothing if the
-  // image is empty.
+  // that either the width and/or height == gfx::kFaviconSize. Does nothing if
+  // the image is empty.
   gfx::Image ResizeFaviconIfNeeded(const gfx::Image& image);
 
   void FetchFaviconInternal();
 
   // Return the current candidate if any.
   FaviconURL* current_candidate() {
-    return (urls_.size() > current_url_index_) ?
-        &urls_[current_url_index_] : NULL;
+    return (image_urls_.size() > 0) ? &image_urls_[0] : NULL;
   }
 
   // Returns the preferred_icon_size according icon_types_, 0 means no
   // preference.
   int preferred_icon_size() {
     return icon_types_ == history::FAVICON ? gfx::kFaviconSize : 0;
   }
 
   // Used for history requests.
   CancelableRequestConsumer cancelable_consumer_;
@@ skipping 12 matching lines @@
   bool favicon_expired_;
 
   // Requests to the renderer to download favicons.
   typedef std::map<int, DownloadRequest> DownloadRequests;
   DownloadRequests download_requests_;
 
   // The combination of the supported icon types.
   const int icon_types_;
 
   // The prioritized favicon candidates from the page back from the renderer.
-  std::vector<FaviconURL> urls_;
-
-  // The current candidate's index in urls_.
-  size_t current_url_index_;
+  std::deque<FaviconURL> image_urls_;
 
   // The FaviconData from history.
   history::FaviconData history_icon_;
 
   // The Profile associated with this handler.
   Profile* profile_;
 
   // This handler's delegate.
   FaviconHandlerDelegate* delegate_;  // weak
 
+  // Current favicon candidate.
+  FaviconCandidate favicon_candidate_;
+
   DISALLOW_COPY_AND_ASSIGN(FaviconHandler);
 };
 
 #endif  // CHROME_BROWSER_FAVICON_FAVICON_HANDLER_H_