Remove PLT.* histograms.

chrome/renderer/chrome_content_renderer_client.cc

Index: chrome/renderer/chrome_content_renderer_client.cc
diff --git a/chrome/renderer/chrome_content_renderer_client.cc b/chrome/renderer/chrome_content_renderer_client.cc
index 0a89b4d677a78b9a6691e90a11d319e1d3c56beb..d698b56293292a01a8584c7d7aa0228436916a82 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -46,7 +46,6 @@
 #include "chrome/renderer/media/chrome_key_systems.h"
 #include "chrome/renderer/net/net_error_helper.h"
 #include "chrome/renderer/net_benchmarking_extension.h"
-#include "chrome/renderer/page_load_histograms.h"
 #include "chrome/renderer/page_load_metrics/metrics_render_frame_observer.h"
 #include "chrome/renderer/pepper/pepper_helper.h"
 #include "chrome/renderer/plugins/non_loadable_plugin_placeholder.h"
@@ -475,12 +474,9 @@ void ChromeContentRendererClient::RenderFrameCreated(
   new NetErrorHelper(render_frame);
 
   if (render_frame->IsMainFrame()) {
-    // Only attach MainRenderFrameObserver to the main frame, since
+    // Only attach MetricsRenderFrameObserver to the main frame, since
     // we only want to log page load metrics for the main frame.
     new page_load_metrics::MetricsRenderFrameObserver(render_frame);
-    // Similarly, PageLoadHistograms are currently only collected for the main
-    // frame.
-    new PageLoadHistograms(render_frame);
   } else {
     // Avoid any race conditions from having the browser tell subframes that
     // they're prerendering.