Refactor download image-MIME-type-detection code.

chrome/browser/download/download_item_model.h

 // Copyright (c) 2012 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_DOWNLOAD_DOWNLOAD_ITEM_MODEL_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_MODEL_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 73 matching lines @@
   // Is this considered a dangerous download?
   bool IsDangerous() const;
 
   // Is this considered a malicious download? Implies IsDangerous().
   bool MightBeMalicious() const;
 
   // Is this considered a malicious download with very high confidence?
   // Implies IsDangerous() and MightBeMalicious().
   bool IsMalicious() const;
 
+  // Does this download have a MIME type (either explicit or inferred from its
+  // extension) suggesting that it is a supported image type?
+  bool HasSupportedImageMimeType() const;
+
   // Is safe browsing download feedback feature available for this download?
   bool ShouldAllowDownloadFeedback() const;
 
   // Returns |true| if this download is expected to complete successfully and
   // thereafter be removed from the shelf.  Downloads that are opened
   // automatically or are temporary will be removed from the shelf on successful
   // completion.
   //
   // Returns |false| if the download is not expected to complete (interrupted,
   // cancelled, dangerous, malicious), or won't be removed on completion.
@@ skipping 72 matching lines @@
 
   // The DownloadItem that this model represents. Note that DownloadItemModel
   // itself shouldn't maintain any state since there can be more than one
   // DownloadItemModel in use with the same DownloadItem.
   content::DownloadItem* download_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadItemModel);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_MODEL_H_