components: Cleanup class/struct fwd declarations

components/history/core/browser/page_usage_data.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_HISTORY_CORE_BROWSER_PAGE_USAGE_DATA_H__
 #define COMPONENTS_HISTORY_CORE_BROWSER_PAGE_USAGE_DATA_H__
 
 #include "base/strings/string16.h"
 #include "components/history/core/browser/history_types.h"
 #include "url/gurl.h"
 
-class SkBitmap;
-
 namespace history {
 
 /////////////////////////////////////////////////////////////////////////////
 //
 // PageUsageData
 //
 // A per domain usage data structure to compute and manage most visited
 // pages.
 //
 // See QueryPageUsageSince()
@@ skipping 36 matching lines @@
   SegmentID id_;
   GURL url_;
   base::string16 title_;
 
   double score_;
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_PAGE_USAGE_DATA_H__