Use TimeTicks as much as possible in startup_metric_utils.

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>
 
@@ skipping 38 matching lines @@
 
 void FirstWebContentsProfiler::DidFirstVisuallyNonEmptyPaint() {
   if (collected_paint_metric_)
     return;
   if (startup_metric_utils::WasNonBrowserUIDisplayed()) {
     FinishedCollectingMetrics(FinishReason::ABANDON_BLOCKING_UI);
     return;
   }
 
   collected_paint_metric_ = true;
-  const base::Time now = base::Time::Now();
+  const base::TimeTicks now = base::TimeTicks::Now();
   // Record the old metric unconditionally.
   startup_metric_utils::RecordDeprecatedFirstWebContentsNonEmptyPaint(now);
   if (!finished_)
     startup_metric_utils::RecordFirstWebContentsNonEmptyPaint(now);
 
   metrics::TrackingSynchronizer::OnProfilingPhaseCompleted(
       metrics::ProfilerEventProto::EVENT_FIRST_NONEMPTY_PAINT);
 
   if (IsFinishedCollectingMetrics())
     FinishedCollectingMetrics(FinishReason::DONE);
 }
 
 void FirstWebContentsProfiler::DocumentOnLoadCompletedInMainFrame() {
   if (collected_load_metric_)
     return;
   if (startup_metric_utils::WasNonBrowserUIDisplayed()) {
     FinishedCollectingMetrics(FinishReason::ABANDON_BLOCKING_UI);
     return;
   }
 
   collected_load_metric_ = true;
-  const base::Time now = base::Time::Now();
+  const base::TimeTicks now = base::TimeTicks::Now();
   // Record the old metric unconditionally.
   startup_metric_utils::RecordDeprecatedFirstWebContentsMainFrameLoad(now);
   if (!finished_)
     startup_metric_utils::RecordFirstWebContentsMainFrameLoad(now);
 
   if (IsFinishedCollectingMetrics())
     FinishedCollectingMetrics(FinishReason::DONE);
 }
 
 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;
   }
 
   // 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::Time::Now());
+      base::TimeTicks::Now());
 }
 
 void FirstWebContentsProfiler::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
   if (collected_main_navigation_finished_metric_) {
     // Abandon profiling on a top-level navigation to a different page as it:
     //   (1) is no longer a fair timing; and
     //   (2) can cause http://crbug.com/525209 where one of the timing
     //       heuristics (e.g. first paint) didn't fire for the initial content
     //       but fires after a lot of idle time when the user finally navigates
@@ skipping 15 matching lines @@
   DCHECK(navigation_handle->IsInMainFrame());
 
   if (!navigation_handle->HasCommitted() ||
       navigation_handle->IsErrorPage()) {
     FinishedCollectingMetrics(FinishReason::ABANDON_NAVIGATION_ERROR);
     return;
   }
 
   collected_main_navigation_finished_metric_ = true;
   startup_metric_utils::RecordFirstWebContentsMainNavigationFinished(
-      base::Time::Now());
+      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);
 }
 
 void FirstWebContentsProfiler::WebContentsDestroyed() {
   FinishedCollectingMetrics(FinishReason::ABANDON_CONTENT_DESTROYED);
@@ skipping 17 matching lines @@
                                 finish_reason, FinishReason::ENUM_MAX);
     }
     finished_ = true;
   }
   // TODO(gab): Delete right away when getting rid of |finished_|.
   if (IsFinishedCollectingMetrics())
     delegate_->ProfilerFinishedCollectingMetrics();
 }
 
 #endif  // !defined(OS_ANDROID)