PageLoadMetrics renderer and browser implementation.

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 a7323cea1cd522c1f9443b76f8820260882f5184..779a8a4cb55243d3705dd389a118073b3d0f2d88 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -62,6 +62,7 @@
 #include "components/nacl/renderer/ppb_nacl_private.h"
 #include "components/nacl/renderer/ppb_nacl_private_impl.h"
 #include "components/network_hints/renderer/prescient_networking_dispatcher.h"
+#include "components/page_load_metrics/renderer/metrics_render_frame_observer.h"
 #include "components/password_manager/content/renderer/credential_manager_client.h"
 #include "components/pdf/renderer/pepper_pdf_host.h"
 #include "components/plugins/renderer/mobile_youtube_plugin.h"
@@ -564,6 +565,12 @@ void ChromeContentRendererClient::RenderFrameCreated(
     new NetErrorHelper(render_frame);
   }
 
+  if (render_frame->GetWebFrame()->parent() == nullptr) {
+    // Only attach MainRenderFrameObserver to the main frame, since
+    // we only want to log page load metrics for the main frame.
+    new page_load_metrics::MetricsRenderFrameObserver(render_frame);
+  }
+
   PasswordAutofillAgent* password_autofill_agent =
       new PasswordAutofillAgent(render_frame);
   PasswordGenerationAgent* password_generation_agent =