Remove the unmaintained performance monitor.

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index 7bde6cd9a54537e86539b1e3179fd99286986710..617aff7dfd8df9120ed83fb64781c1dc7c7ec8ea 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -342,12 +342,6 @@ bool NavigatorImpl::NavigateToEntry(
   // capture the time needed for the RenderFrameHost initialization.
   base::TimeTicks navigation_start = base::TimeTicks::Now();
 
-  // WebContents uses this to fill LoadNotificationDetails when the load
-  // completes, so that PerformanceMonitor that listens to the notification can
-  // record the load time. PerformanceMonitor is no longer maintained.
-  // TODO(ppi): make this go away.
-  current_load_start_ = base::TimeTicks::Now();
-
   // Create the navigation parameters.
   FrameMsg_Navigate_Params navigate_params;
   MakeNavigateParams(
@@ -429,10 +423,6 @@ bool NavigatorImpl::NavigateToPendingEntry(
       reload_type);
 }
 
-base::TimeTicks NavigatorImpl::GetCurrentLoadStart() {
-  return current_load_start_;
-}
-
 void NavigatorImpl::DidNavigate(
     RenderFrameHostImpl* render_frame_host,
     const FrameHostMsg_DidCommitProvisionalLoad_Params& input_params) {