customtabs: Send time to first contentful paint to the caller.

components/page_load_metrics/browser/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 "components/page_load_metrics/browser/metrics_web_contents_observer.h"
 
 #include <algorithm>
 #include <ostream>
 #include <string>
 #include <utility>
@@ skipping 247 matching lines @@
     int aborted_chain_size_same_url)
     : renderer_tracked_(false),
       navigation_start_(navigation_handle->NavigationStart()),
       url_(navigation_handle->GetURL()),
       abort_type_(ABORT_NONE),
       started_in_foreground_(in_foreground),
       aborted_chain_size_(aborted_chain_size),
       aborted_chain_size_same_url_(aborted_chain_size_same_url),
       embedder_interface_(embedder_interface) {
   DCHECK(!navigation_handle->HasCommitted());
-  embedder_interface_->RegisterObservers(this);
+  embedder_interface_->RegisterObservers(this,
+                                         navigation_handle->GetWebContents());
   for (const auto& observer : observers_) {
     observer->OnStart(navigation_handle, currently_committed_url,
                       started_in_foreground_);
   }
 }
 
 PageLoadTracker::~PageLoadTracker() {
   const PageLoadExtraInfo info = ComputePageLoadExtraInfo();
 
   if (info.time_to_commit && renderer_tracked() && timing_.IsEmpty()) {
@@ skipping 644 matching lines @@
 
   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);
   }
 }
 
 }  // namespace page_load_metrics