Add startup metrics that measure the performance of the first web contents.

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"
@@ skipping 246 matching lines @@
   const int kStartupMetricsGatheringDelaySeconds = 45;
   content::BrowserThread::GetBlockingPool()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&RecordStartupMetricsOnBlockingPool),
       base::TimeDelta::FromSeconds(kStartupMetricsGatheringDelaySeconds));
 
   display_count_ = gfx::Screen::GetNativeScreen()->GetNumDisplays();
   UMA_HISTOGRAM_COUNTS_100("Hardware.Display.Count.OnStartup", display_count_);
   gfx::Screen::GetNativeScreen()->AddObserver(this);
   is_screen_observer_ = true;
+
+  if (FirstWebContentsProfiler::ShouldCollectMetrics()) {
+    first_web_contents_profiler_ =
+        FirstWebContentsProfiler::CreateProfilerForFirstWebContents(this)
+            .Pass();
+  }
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayAdded(
     const gfx::Display& new_display) {
   EmitDisplaysChangedMetric();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayRemoved(
     const gfx::Display& old_display) {
   EmitDisplaysChangedMetric();
 }
 
 void ChromeBrowserMainExtraPartsMetrics::OnDisplayMetricsChanged(
     const gfx::Display& display,
     uint32_t changed_metrics) {
 }
 
+void ChromeBrowserMainExtraPartsMetrics::ProfilerFinishedCollectingMetrics() {
+  first_web_contents_profiler_.reset();
+}
+
 void ChromeBrowserMainExtraPartsMetrics::EmitDisplaysChangedMetric() {
   int display_count = gfx::Screen::GetNativeScreen()->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