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

components/html_viewer/stats_collection_observer.cc

Index: components/html_viewer/stats_collection_observer.cc
diff --git a/content/renderer/stats_collection_observer.cc b/components/html_viewer/stats_collection_observer.cc
similarity index 56%
copy from content/renderer/stats_collection_observer.cc
copy to components/html_viewer/stats_collection_observer.cc
index 4c4b911ec8cbedb9cdf0858ec590b48701c0f73a..2efb5f4ca60b4b8d6d547dc0c8998780f6148699 100644
--- a/content/renderer/stats_collection_observer.cc
+++ b/components/html_viewer/stats_collection_observer.cc
@@ -2,15 +2,12 @@
 // 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() {
@@ -26,8 +23,7 @@ void StatsCollectionObserver::DidStopLoading() {
   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