Replace base::Timer with behavior-specific timers in enrollment/ and policy/

This CL replaces base::Timer with its subclasses.
As base::Timer changes its behavior subject to its construction time
flags, that makes hard to see the actual timer behavior, especially
it's unclear when a timer is injected from other components.
Also, that OnceCallback support of base::Timer is hard to implement on
the dynamically determined invocation pattern.

Bug: 850247
Change-Id: If83f289ad4c284f21d297b813d7ad25e68a2dd5b
Reviewed-on: https://chromium-review.googlesource.com/1130561Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573989}

chrome/browser/chromeos/login/enrollment/auto_enrollment_controller.cc

@@ -249,8 +249,7 @@ class AutoEnrollmentController::SystemClockSyncWaiter
   // or a timeout has been reached.
   std::vector<SystemClockSyncCallback> system_clock_sync_callbacks_;
 
-  base::Timer timeout_timer_{false /* retain_user_task */,
-                             false /* is_repeating */};
+  base::OneShotTimer timeout_timer_;
 
   base::WeakPtrFactory<SystemClockSyncWaiter> weak_ptr_factory_{this};
 

chrome/browser/chromeos/login/enrollment/auto_enrollment_controller.h

@@ -237,8 +237,7 @@ class AutoEnrollmentController {
   // something goes wrong, the timer will ensure that a decision gets made
   // eventually, which is crucial to not block OOBE forever. See
   // http://crbug.com/433634 for background.
-  base::Timer safeguard_timer_{false /* retain_user_task */,
-                               false /* is_repeating */};
+  base::OneShotTimer safeguard_timer_;
 
   // Whether the forced re-enrollment check has to be applied.
   FRERequirement fre_requirement_ = FRERequirement::kRequired;

chrome/browser/chromeos/policy/active_directory_policy_manager.h

@@ -175,8 +175,7 @@ class UserActiveDirectoryPolicyManager : public ActiveDirectoryPolicyManager {
 
   // A timer that puts a hard limit on the maximum time to wait for the initial
   // policy fetch/load.
-  base::Timer initial_policy_timeout_{false /* retain_user_task */,
-                                      false /* is_repeating */};
+  base::OneShotTimer initial_policy_timeout_;
 
   // Callback to exit the session.
   base::OnceClosure exit_session_;

chrome/browser/chromeos/policy/pre_signin_policy_fetcher.h

@@ -149,7 +149,7 @@ class PreSigninPolicyFetcher : public CloudPolicyClient::Observer {
 
   // A timer that puts a hard limit on the maximum time to wait for the fresh
   // policy fetch.
-  base::Timer policy_fetch_timeout_{false, false};
+  base::OneShotTimer policy_fetch_timeout_;
 
   // Used to load the policy key provided by session manager as a file.
   std::unique_ptr<CachedPolicyKeyLoaderChromeOS> cached_policy_key_loader_;

chrome/browser/chromeos/policy/user_cloud_policy_manager_chromeos.h

@@ -247,8 +247,7 @@ class UserCloudPolicyManagerChromeOS : public CloudPolicyManager,
 
   // A timer that puts a hard limit on the maximum time to wait for a policy
   // refresh.
-  base::Timer policy_refresh_timeout_{false /* retain_user_task */,
-                                      false /* is_repeating */};
+  base::OneShotTimer policy_refresh_timeout_;
 
   // The pref service to pass to the refresh scheduler on initialization.
   PrefService* local_state_;