Provision to start base::SimpleTestTickClock at initial ticks

components/scheduler/renderer/user_model_unittest.cc

 // Copyright 2015 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 "components/scheduler/renderer/user_model.h"
 
 #include "base/test/simple_test_tick_clock.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace scheduler {
 
 class UserModelTest : public testing::Test {
  public:
   UserModelTest() {}
   ~UserModelTest() override {}
 
   void SetUp() override {
-    clock_.reset(new base::SimpleTestTickClock());
-    clock_->Advance(base::TimeDelta::FromMicroseconds(5000));
-
+    clock_.reset(new base::SimpleTestTickClock(
+        base::TimeTicks() + base::TimeDelta::FromMicroseconds(5000)));
     user_model_.reset(new UserModel());
   }
 
  protected:
   static base::TimeDelta priority_escalation_after_input_duration() {
     return base::TimeDelta::FromMilliseconds(
         UserModel::kGestureEstimationLimitMillis);
   }
 
   static base::TimeDelta subsequent_input_expected_after_input_duration() {
@@ skipping 213 matching lines @@
       UserModel::kMedianGestureDurationMillis * 2));
   clock_->Advance(delta);
 
   base::TimeDelta prediction_valid_duration;
   EXPECT_FALSE(user_model_->IsGestureExpectedToContinue(
       clock_->NowTicks(), &prediction_valid_duration));
   EXPECT_EQ(base::TimeDelta(), prediction_valid_duration);
 }
 
 }  // namespace scheduler