Add browser test for NavigationMetricsRecorder

chrome/browser/tab_contents/navigation_metrics_recorder.h

Index: chrome/browser/tab_contents/navigation_metrics_recorder.h
diff --git a/chrome/browser/tab_contents/navigation_metrics_recorder.h b/chrome/browser/tab_contents/navigation_metrics_recorder.h
index 80d0ac0f8069cf0f37a2368539235b7e4f68617e..c2fbd202ecf5c4eaac69a02f056a24473f30469a 100644
--- a/chrome/browser/tab_contents/navigation_metrics_recorder.h
+++ b/chrome/browser/tab_contents/navigation_metrics_recorder.h
@@ -9,12 +9,18 @@
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
+namespace rappor {
+class RapporService;
+}
+
 class NavigationMetricsRecorder
     : public content::WebContentsObserver,
       public content::WebContentsUserData<NavigationMetricsRecorder> {
  public:
   ~NavigationMetricsRecorder() override;
 
+  void set_rappor_service_for_testing(rappor::RapporService* rappor_service);
+
  private:
   explicit NavigationMetricsRecorder(content::WebContents* web_contents);
   friend class content::WebContentsUserData<NavigationMetricsRecorder>;
@@ -24,6 +30,8 @@ class NavigationMetricsRecorder
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) override;
 
+  rappor::RapporService* rappor_service_;
+
   DISALLOW_COPY_AND_ASSIGN(NavigationMetricsRecorder);
 };