Fix for URL opening code

chrome/browser/metrics/chrome_browser_main_extra_parts_metrics.cc

 // Copyright (c) 2013 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/metrics/chrome_browser_main_extra_parts_metrics.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/cpu.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/sys_info.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_browser_main.h"
 #include "chrome/browser/mac/bluetooth_utility.h"
 #include "chrome/browser/shell_integration.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/flags_ui/pref_service_flags_storage.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/content_switches.h"
 #include "ui/base/touch/touch_device.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/display/screen.h"
 
 #if !defined(OS_ANDROID)
 #include "chrome/browser/metrics/first_web_contents_profiler.h"
 #include "chrome/browser/metrics/tab_usage_recorder.h"
@@ skipping 379 matching lines @@
       base::Bind(&RecordIsPinnedToTaskbarHistogram),
       kStartupMetricsGatheringDelay);
 #endif  // defined(OS_WIN)
 
   display_count_ = display::Screen::GetScreen()->GetNumDisplays();
   UMA_HISTOGRAM_COUNTS_100("Hardware.Display.Count.OnStartup", display_count_);
   display::Screen::GetScreen()->AddObserver(this);
   is_screen_observer_ = true;
 
 #if !defined(OS_ANDROID)
-  metrics::BeginFirstWebContentsProfiling();
+  const BrowserList* browser_list = BrowserList::GetInstance();
+
+  auto first_browser = browser_list->begin();
+  if (first_browser == browser_list->end())
+    DCHECK(0);

[sky, 2017/04/07 21:52:14]

I'm not entirely sure it's valid to assume there is at least one browser. In
particular starting up in background mode (or other similar things) may result
in no browsers.

[eugenebng, 2017/04/10 12:04:43]

Thank you for comments, overlooked this part of code. Have to fix this if the
code will not be completely changed/rewritten in the first place.

+
+  TabStripModel* tab_strip = (*first_browser)->tab_strip_model();
+  DCHECK(tab_strip);
+  if (tab_strip->empty()) {
+    // Start web contents profiling later, when there will be a tab to profile
+    tab_strip->AddObserver(this);

[sky, 2017/04/07 21:52:14]

Make sure you deal with case of this being deleted before TabInsertAt.

+  } else {
+    metrics::BeginFirstWebContentsProfiling();
+  }
   metrics::TabUsageRecorder::InitializeIfNeeded();
 #endif  // !defined(OS_ANDROID)
 }
 
+void ChromeBrowserMainExtraPartsMetrics::TabInsertedAt(
+    TabStripModel* tab_strip_model,
+    content::WebContents* contents,
+    int index,
+    bool foreground) {
+  VLOG(0) << "begin profiling!";

[sky, 2017/04/07 21:52:14]

Remove VLOGs.

+  metrics::BeginFirstWebContentsProfiling();
+  tab_strip_model->RemoveObserver(this);
+}
+
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayAdded(
     const display::Display& new_display) {
   EmitDisplaysChangedMetric();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayRemoved(
     const display::Display& old_display) {
   EmitDisplaysChangedMetric();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayMetricsChanged(
     const display::Display& display,
     uint32_t changed_metrics) {}
 
 void ChromeBrowserMainExtraPartsMetrics::EmitDisplaysChangedMetric() {
   int display_count = display::Screen::GetScreen()->GetNumDisplays();
   if (display_count != display_count_) {
     display_count_ = display_count;
     UMA_HISTOGRAM_COUNTS_100("Hardware.Display.Count.OnChange", display_count_);
   }
 }
 
 namespace chrome {
 
 void AddMetricsExtraParts(ChromeBrowserMainParts* main_parts) {
   main_parts->AddParts(new ChromeBrowserMainExtraPartsMetrics());
 }
 
 }  // namespace chrome