Add stats collection for telemetry startup.warm.blank_page test.

components/html_viewer/stats_collection_observer.cc

 // Copyright 2013 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 "content/renderer/stats_collection_observer.h"
+#include "components/html_viewer/stats_collection_observer.h"
 
-#include "base/time/time.h"
-#include "content/renderer/render_view_impl.h"
+namespace html_viewer {
 
-namespace content {
-
-StatsCollectionObserver::StatsCollectionObserver(RenderViewImpl* render_view)
-    : RenderViewObserver(render_view) {
+StatsCollectionObserver::StatsCollectionObserver(HTMLDocument* html_document)
+  : HTMLDocument::Observer(html_document) {
 }
 
 StatsCollectionObserver::~StatsCollectionObserver() {
 }
 
 void StatsCollectionObserver::DidStartLoading() {
   DCHECK(start_time_.is_null());
   start_time_ = base::Time::Now();
 }
 
 void StatsCollectionObserver::DidStopLoading() {
   DCHECK(stop_time_.is_null());
   stop_time_ = base::Time::Now();
 
   // Stop observing so we don't get called again.
-  RenderViewImpl* impl = static_cast<RenderViewImpl*>(render_view());
-  impl->RemoveObserver(this);
+  html_document()->RemoveObserver(this);
 }
 
-}  // namespace content
+}  // namespace html_viewer