Add support for tracking loading behavior of child frames.

chrome/browser/page_load_metrics/metrics_web_contents_observer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/page_load_metrics/metrics_web_contents_observer.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 492 matching lines @@
   }
 
   aborted_provisional_loads_.clear();
   return last_aborted_load;
 }
 
 void MetricsWebContentsObserver::OnTimingUpdated(
     content::RenderFrameHost* render_frame_host,
     const PageLoadTiming& timing,
     const PageLoadMetadata& metadata) {
+  content::RenderFrameHost* root_render_frame_host = render_frame_host;

[Charlie Harrison, 2017/03/08 21:47:17]

I would probably prefer GetRenderViewHost()->GetMainFrame() so you don't have to
walk the frame tree.

[Bryan McQuade, 2017/03/09 03:06:11]

ah, absolutely, thanks! didn't know about that.

+  while (root_render_frame_host->GetParent() != nullptr) {
+    root_render_frame_host = root_render_frame_host->GetParent();
+  }
+
   // We may receive notifications from frames that have been navigated away
   // from. We simply ignore them.
-  if (render_frame_host != web_contents()->GetMainFrame()) {
+  if (root_render_frame_host != web_contents()->GetMainFrame()) {
     RecordInternalError(ERR_IPC_FROM_WRONG_FRAME);
     return;
   }
 
   // While timings arriving for the wrong frame are expected, we do not expect
   // any of the errors below. Thus, we track occurrences of all errors below,
   // rather than returning early after encountering an error.
 
   bool error = false;
   if (!committed_load_) {
     RecordInternalError(ERR_IPC_WITH_NO_RELEVANT_LOAD);
     error = true;
   }
 
   if (!web_contents()->GetLastCommittedURL().SchemeIsHTTPOrHTTPS()) {
     RecordInternalError(ERR_IPC_FROM_BAD_URL_SCHEME);
     error = true;
   }
 
   if (error)
     return;
 
+  if (render_frame_host->GetParent() != nullptr) {
+    // Child frames may send PageLoadMetadata updates, but not PageLoadTiming
+    // updates.
+    if (!timing.IsEmpty())
+      RecordInternalError(ERR_TIMING_IPC_FROM_SUBFRAME);
+    committed_load_->UpdateChildMetadata(metadata);
+    return;
+  }
+
   if (!committed_load_->UpdateTiming(timing, metadata)) {
     // If the page load tracker cannot update its timing, something is wrong
     // with the IPC (it's from another load, or it's invalid in some other way).
     // We expect this to be a rare occurrence.
     RecordInternalError(ERR_BAD_TIMING_IPC);
   }
 }
 
 bool MetricsWebContentsObserver::ShouldTrackNavigation(
     content::NavigationHandle* navigation_handle) const {
   DCHECK(navigation_handle->IsInMainFrame());
   DCHECK(!navigation_handle->HasCommitted() ||
          !navigation_handle->IsSameDocument());
 
   return BrowserPageTrackDecider(embedder_interface_.get(), web_contents(),
                                  navigation_handle).ShouldTrack();
 }
 
 }  // namespace page_load_metrics