Add TODO to remove page_load_histograms.h/.cc

chrome/renderer/page_load_histograms.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.
 
+// TODO(bmcquade): delete this class in October 2016, as it is deprecated by the
+// new PageLoad.* UMA histograms.
+
 #ifndef CHROME_RENDERER_PAGE_LOAD_HISTOGRAMS_H_
 #define CHROME_RENDERER_PAGE_LOAD_HISTOGRAMS_H_
 
 #include "base/macros.h"
 #include "content/public/renderer/render_view_observer.h"
 
 namespace blink {
 class WebDataSource;
 }
 
@@ skipping 33 matching lines @@
   // so first_paint and first_paint_after_load can be 0.
   void Dump(blink::WebFrame* frame);
 
   void LogPageLoadTime(const content::DocumentState* load_times,
                        const blink::WebDataSource* ds) const;
 
   DISALLOW_COPY_AND_ASSIGN(PageLoadHistograms);
 };
 
 #endif  // CHROME_RENDERER_PAGE_LOAD_HISTOGRAMS_H_