ArcSessionManager : Use TimeTicks for arc_start_time and sign_in_start_time

Also update ArcPolicyBridge, the sole user of these time values.

Context : We have been using SessionManagerImpl::GetArcStartTimeTicks()
for perf measurements, etc, but this doesn't work for ARCVM.
This CL makes ArcSessionManager.arc_start_time() equivalent to
SessionManagerImpl::GetArcStartTimeTicks() by using TimeTicks.

Bug: b/140361966
Test: try
Change-Id: Ic935ccdf8b2177abb0644551a3b422a5e5c0c25c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1783687Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: Satoshi Niwa <niwa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693157}

chrome/browser/chromeos/arc/arc_session_manager.cc

@@ -336,7 +336,7 @@ void ArcSessionManager::OnProvisioningFinished(ProvisioningResult result) {
   } else if (!sign_in_start_time_.is_null()) {
     arc_sign_in_timer_.Stop();
 
-    UpdateProvisioningTiming(base::Time::Now() - sign_in_start_time_,
+    UpdateProvisioningTiming(base::TimeTicks::Now() - sign_in_start_time_,
                              provisioning_successful, profile_);
     UpdateProvisioningResultUMA(result, profile_);
     if (!provisioning_successful)
@@ -930,7 +930,7 @@ void ArcSessionManager::OnAndroidManagementChecked(
   switch (result) {
     case policy::AndroidManagementClient::Result::UNMANAGED:
       VLOG(1) << "Starting ARC for first sign in.";
-      sign_in_start_time_ = base::Time::Now();
+      sign_in_start_time_ = base::TimeTicks::Now();
       arc_sign_in_timer_.Start(
           FROM_HERE, kArcSignInTimeout,
           base::Bind(&ArcSessionManager::OnArcSignInTimeout,
@@ -1007,7 +1007,7 @@ void ArcSessionManager::StartArc() {
   for (auto& observer : observer_list_)
     observer.OnArcStarted();
 
-  arc_start_time_ = base::Time::Now();
+  arc_start_time_ = base::TimeTicks::Now();
   provisioning_reported_ = false;
 
   std::string locale;

chrome/browser/chromeos/arc/arc_session_manager.h

@@ -221,11 +221,11 @@ class ArcSessionManager : public ArcSessionRunner::Observer,
 
   // Returns the time when the sign in process started, or a null time if
   // signing in didn't happen during this session.
-  base::Time sign_in_start_time() const { return sign_in_start_time_; }
+  base::TimeTicks sign_in_start_time() const { return sign_in_start_time_; }
 
   // Returns the time when ARC was about to start, or a null time if ARC has not
   // been started yet.
-  base::Time arc_start_time() const { return arc_start_time_; }
+  base::TimeTicks arc_start_time() const { return arc_start_time_; }
 
   // Returns true if ARC requested to start.
   bool enable_requested() const { return enable_requested_; }
@@ -377,9 +377,9 @@ class ArcSessionManager : public ArcSessionRunner::Observer,
   std::unique_ptr<ArcFastAppReinstallStarter> fast_app_reinstall_starter_;
 
   // The time when the sign in process started.
-  base::Time sign_in_start_time_;
+  base::TimeTicks sign_in_start_time_;
   // The time when ARC was about to start.
-  base::Time arc_start_time_;
+  base::TimeTicks arc_start_time_;
   base::Closure attempt_user_exit_callback_;
 
   ArcAppIdProviderImpl app_id_provider_;

chrome/browser/chromeos/arc/policy/arc_policy_bridge.cc

@@ -494,7 +494,7 @@ void ArcPolicyBridge::OnPolicyUpdated(const policy::PolicyNamespace& ns,
   const std::string policies_hash = GetPoliciesHash(GetCurrentJSONPolicies());
   if (policies_hash != update_notification_policies_hash_) {
     update_notification_policies_hash_ = policies_hash;
-    update_notification_time_ = base::Time::Now();
+    update_notification_time_ = base::TimeTicks::Now();
     compliance_since_update_timing_reported_ = false;
   }
 
@@ -574,12 +574,13 @@ void ArcPolicyBridge::UpdateComplianceReportMetrics(
   if (!is_arc_plus_plus_report_successful || reported_policies_hash.empty())
     return;
 
-  const base::Time now = base::Time::Now();
+  const base::TimeTicks now = base::TimeTicks::Now();
   ArcSessionManager* const session_manager = ArcSessionManager::Get();
 
   if (reported_policies_hash == initial_policies_hash_ &&
       !first_compliance_timing_reported_) {
-    const base::Time sign_in_start_time = session_manager->sign_in_start_time();
+    const base::TimeTicks sign_in_start_time =
+        session_manager->sign_in_start_time();
     if (!sign_in_start_time.is_null()) {
       UpdateFirstComplianceSinceSignInTiming(now - sign_in_start_time);
     } else {

chrome/browser/chromeos/arc/policy/arc_policy_bridge.h

@@ -189,7 +189,7 @@ class ArcPolicyBridge : public KeyedService,
   std::string update_notification_policies_hash_;
   // The time of the policy update notification sent when the policy with hash
   // equal to |update_notification_policy_hash_| was active.
-  base::Time update_notification_time_;
+  base::TimeTicks update_notification_time_;
   // Whether the UMA metric for the successfully obtained compliance report
   // since the most recent policy update notificaton was already reported.
   bool compliance_since_update_timing_reported_ = false;