Remove dead flush histograms code.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 8ea4bb12aade5984c278edfbd451a37fde8103f0..cbffff5b64a755610e00c09d9efd43324926e9a8 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -1439,10 +1439,6 @@ void RenderThreadImpl::SetIdleNotificationDelayInMs(
   idle_notification_delay_in_ms_ = idle_notification_delay_in_ms;
 }
 
-void RenderThreadImpl::UpdateHistograms(int sequence_number) {
-  child_histogram_message_filter()->SendHistograms(sequence_number);
-}
-
 int RenderThreadImpl::PostTaskToAllWebWorkers(const base::Closure& closure) {
   return WorkerThreadRegistry::Instance()->PostTaskToAllThreads(closure);
 }