Implement "Save image as" for canvas (chromium side).

chrome/browser/renderer_context_menu/context_menu_content_type.cc

 // 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.
 
 #include "chrome/browser/renderer_context_menu/context_menu_content_type.h"
 
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/common/url_constants.h"
@@ skipping 109 matching lines @@
     case ITEM_GROUP_SEARCHWEBFORIMAGE:
       // Image menu items imply search web for image item.
       return SupportsGroupInternal(ITEM_GROUP_MEDIA_IMAGE);
 
     case ITEM_GROUP_MEDIA_VIDEO:
       return params_.media_type == WebContextMenuData::MediaTypeVideo;
 
     case ITEM_GROUP_MEDIA_AUDIO:
       return params_.media_type == WebContextMenuData::MediaTypeAudio;
 
+    case ITEM_GROUP_MEDIA_CANVAS:
+      return params_.media_type == WebContextMenuData::MediaTypeCanvas;
+
     case ITEM_GROUP_MEDIA_PLUGIN:
       return params_.media_type == WebContextMenuData::MediaTypePlugin;
 
     case ITEM_GROUP_MEDIA_FILE:
 #if defined(WEBCONTEXT_MEDIATYPEFILE_DEFINED)
       return params_.media_type == WebContextMenuData::MediaTypeFile;
 #else
       return false;
 #endif
 
@@ skipping 29 matching lines @@
       return true;
 #else
       return false;
 #endif
 
     default:
       NOTREACHED();
       return false;
   }
 }