A different approach to fixing FirstWebContentsProfiler with PlzNavigate.

chrome/browser/metrics/first_web_contents_profiler.cc

 // Copyright 2014 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.
 
 #if !defined(OS_ANDROID)
 
 #include "chrome/browser/metrics/first_web_contents_profiler.h"
 
 #include <string>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "components/metrics/profiler/tracking_synchronizer.h"
 #include "components/metrics/proto/profiler_event.pb.h"
 #include "components/startup_metric_utils/browser/startup_metric_utils.h"
 #include "content/public/browser/navigation_handle.h"
+#include "content/public/common/browser_side_navigation_policy.h"
 
-void FirstWebContentsProfiler::WebContentsStarted(
-    content::WebContents* web_contents) {
-  static bool first_web_contents_profiled = false;
-  if (first_web_contents_profiled)
-    return;
-
-  first_web_contents_profiled = true;
-  new FirstWebContentsProfiler(web_contents);
+// static
+void FirstWebContentsProfiler::Start() {
+  for (auto* browser : *BrowserList::GetInstance()) {
+    content::WebContents* web_contents =
+        browser->tab_strip_model()->GetActiveWebContents();
+    if (web_contents) {
+      // FirstWebContentsProfiler owns itself and is also bound to
+      // |web_contents|'s lifetime by observing WebContentsDestroyed().
+      new FirstWebContentsProfiler(web_contents);
+      return;
+    }
+  }
 }
 
 FirstWebContentsProfiler::FirstWebContentsProfiler(
     content::WebContents* web_contents)
     : content::WebContentsObserver(web_contents),
       collected_paint_metric_(false),
       collected_load_metric_(false),
       collected_main_navigation_start_metric_(false),
       collected_main_navigation_finished_metric_(false) {}
 
@@ skipping 34 matching lines @@
 
 void FirstWebContentsProfiler::DidStartNavigation(
     content::NavigationHandle* navigation_handle) {
   if (collected_main_navigation_start_metric_)
     return;
   if (startup_metric_utils::WasNonBrowserUIDisplayed()) {
     FinishedCollectingMetrics(FinishReason::ABANDON_BLOCKING_UI);
     return;
   }
 
+  if (content::IsBrowserSideNavigationEnabled()) {
+    // With PlzNavigate, DidStartNavigation is called synchronously on
+    // browser-initiated loads instead of through an IPC. This means that we
+    // will miss this signal. Instead we record it when the commit completes.
+    return;
+  }
+
   // The first navigation has to be the main frame's.
   DCHECK(navigation_handle->IsInMainFrame());
 
   collected_main_navigation_start_metric_ = true;
   startup_metric_utils::RecordFirstWebContentsMainNavigationStart(
       base::TimeTicks::Now());
 }
 
 void FirstWebContentsProfiler::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
@@ skipping 19 matching lines @@
 
   // The first navigation has to be the main frame's.
   DCHECK(navigation_handle->IsInMainFrame());
 
   if (!navigation_handle->HasCommitted() ||
       navigation_handle->IsErrorPage()) {
     FinishedCollectingMetrics(FinishReason::ABANDON_NAVIGATION_ERROR);
     return;
   }
 
+  if (content::IsBrowserSideNavigationEnabled()) {
+    startup_metric_utils::RecordFirstWebContentsMainNavigationStart(
+        navigation_handle->NavigationStart());
+    collected_main_navigation_start_metric_ = true;
+  }
+
   collected_main_navigation_finished_metric_ = true;
   startup_metric_utils::RecordFirstWebContentsMainNavigationFinished(
       base::TimeTicks::Now());
 }
 
 void FirstWebContentsProfiler::WasHidden() {
   // Stop profiling if the content gets hidden as its load may be deprioritized
   // and timing it becomes meaningless.
   FinishedCollectingMetrics(FinishReason::ABANDON_CONTENT_HIDDEN);
 }
@@ skipping 16 matching lines @@
   }
   if (!collected_load_metric_) {
     UMA_HISTOGRAM_ENUMERATION("Startup.FirstWebContents.FinishReason_NoLoad",
                               finish_reason, FinishReason::ENUM_MAX);
   }
 
   delete this;
 }
 
 #endif  // !defined(OS_ANDROID)