Convert base::Clock::Now() a const method

This method should be a const method to be consistent to NowTicks() in
base::TickClock, which is also converted to a const method at
http://crrev.com/821f0e338ebbe420

Bug: 789079
Change-Id: I6b5c9bcee2d730214298ae7a7136ea6b312ad079
Reviewed-on: https://chromium-review.googlesource.com/1001213
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550598}

base/test/simple_test_clock.cc

@@ -10,7 +10,7 @@ SimpleTestClock::SimpleTestClock() = default;
 
 SimpleTestClock::~SimpleTestClock() = default;
 
-Time SimpleTestClock::Now() {
+Time SimpleTestClock::Now() const {
   AutoLock lock(lock_);
   return now_;
 }

base/test/simple_test_clock.h

@@ -21,7 +21,7 @@ class SimpleTestClock : public Clock {
   SimpleTestClock();
   ~SimpleTestClock() override;
 
-  Time Now() override;
+  Time Now() const override;
 
   // Advances the clock by |delta|.
   void Advance(TimeDelta delta);
@@ -31,7 +31,7 @@ class SimpleTestClock : public Clock {
 
  private:
   // Protects |now_|.
-  Lock lock_;
+  mutable Lock lock_;
 
   Time now_;
 };

base/test/test_mock_time_task_runner.cc

@@ -42,7 +42,7 @@ class LegacyMockClock : public Clock {
       : task_runner_(std::move(task_runner)) {}
 
   // Clock:
-  Time Now() override { return task_runner_->Now(); }
+  Time Now() const override { return task_runner_->Now(); }
 
  private:
   scoped_refptr<const TestMockTimeTaskRunner> task_runner_;
@@ -417,7 +417,7 @@ TimeTicks TestMockTimeTaskRunner::MockClock::NowTicks() const {
   return task_runner_->NowTicks();
 }
 
-Time TestMockTimeTaskRunner::MockClock::Now() {
+Time TestMockTimeTaskRunner::MockClock::Now() const {
   return task_runner_->Now();
 }
 

base/test/test_mock_time_task_runner.h

@@ -212,7 +212,7 @@ class TestMockTimeTaskRunner : public SingleThreadTaskRunner,
     TimeTicks NowTicks() const override;
 
     // Clock:
-    Time Now() override;
+    Time Now() const override;
 
    private:
     TestMockTimeTaskRunner* task_runner_;

base/time/clock.h

@@ -32,7 +32,7 @@ class BASE_EXPORT Clock {
   // Now() must be safe to call from any thread.  The caller cannot
   // make any ordering assumptions about the returned Time.  For
   // example, the system clock may change to an earlier time.
-  virtual Time Now() = 0;
+  virtual Time Now() const = 0;
 };
 
 }  // namespace base

base/time/default_clock.cc

@@ -10,7 +10,7 @@ namespace base {
 
 DefaultClock::~DefaultClock() = default;
 
-Time DefaultClock::Now() {
+Time DefaultClock::Now() const {
   return Time::Now();
 }
 

base/time/default_clock.h

@@ -17,7 +17,7 @@ class BASE_EXPORT DefaultClock : public Clock {
   ~DefaultClock() override;
 
   // Simply returns Time::Now().
-  Time Now() override;
+  Time Now() const override;
 
   // Returns a shared instance of DefaultClock. This is thread-safe.
   static DefaultClock* GetInstance();

chrome/browser/chromeos/night_light/night_light_client_unittest.cc

@@ -72,7 +72,7 @@ class FakeNightLightClient : public NightLightClient,
   ~FakeNightLightClient() override = default;
 
   // base::Clock:
-  base::Time Now() override { return fake_now_; }
+  base::Time Now() const override { return fake_now_; }
 
   // base::TickClock:
   base::TimeTicks NowTicks() const override { return fake_now_ticks_; }

chrome/browser/extensions/test_extension_prefs.cc

@@ -52,13 +52,13 @@ class TestExtensionPrefs::IncrementalClock : public base::Clock {
 
   ~IncrementalClock() override {}
 
-  base::Time Now() override {
+  base::Time Now() const override {
     current_time_ += base::TimeDelta::FromSeconds(10);
     return current_time_;
   }
 
  private:
-  base::Time current_time_;
+  mutable base::Time current_time_;
 
   DISALLOW_COPY_AND_ASSIGN(IncrementalClock);
 };

components/data_reduction_proxy/core/browser/data_reduction_proxy_test_utils.cc

@@ -198,8 +198,8 @@ TestDataReductionProxyConfigServiceClient::TestTickClock::NowTicks() const {
   return base::TimeTicks::UnixEpoch() + (time_ - base::Time::UnixEpoch());
 }
 
-base::Time
-TestDataReductionProxyConfigServiceClient::TestTickClock::Now() {
+base::Time TestDataReductionProxyConfigServiceClient::TestTickClock::Now()
+    const {
   return time_;
 }
 

components/data_reduction_proxy/core/browser/data_reduction_proxy_test_utils.h

@@ -155,7 +155,7 @@ class TestDataReductionProxyConfigServiceClient
     base::TimeTicks NowTicks() const override;
 
     // base::Clock implementation.
-    base::Time Now() override;
+    base::Time Now() const override;
 
     // Sets the current time.
     void SetTime(const base::Time& time);

components/domain_reliability/test_util.cc

@@ -121,7 +121,9 @@ MockTime::MockTime()
 
 MockTime::~MockTime() {}
 
-base::Time MockTime::Now() { return now_; }
+base::Time MockTime::Now() const {
+  return now_;
+}
 base::TimeTicks MockTime::NowTicks() const {
   return now_ticks_;
 }

components/domain_reliability/test_util.h

@@ -75,7 +75,7 @@ class MockTime : public MockableTime {
   ~MockTime() override;
 
   // MockableTime implementation:
-  base::Time Now() override;
+  base::Time Now() const override;
   base::TimeTicks NowTicks() const override;
   std::unique_ptr<MockableTime::Timer> CreateTimer() override;
 

components/domain_reliability/util.cc

@@ -241,7 +241,9 @@ MockableTime::MockableTime() {}
 ActualTime::ActualTime() {}
 ActualTime::~ActualTime() {}
 
-base::Time ActualTime::Now() { return base::Time::Now(); }
+base::Time ActualTime::Now() const {
+  return base::Time::Now();
+}
 base::TimeTicks ActualTime::NowTicks() const {
   return base::TimeTicks::Now();
 }

components/domain_reliability/util.h

@@ -82,7 +82,7 @@ class DOMAIN_RELIABILITY_EXPORT MockableTime : public base::Clock,
   ~MockableTime() override;
 
   // Clock impl; returns base::Time::Now() or a mocked version thereof.
-  base::Time Now() override = 0;
+  base::Time Now() const override = 0;
   // TickClock impl; returns base::TimeTicks::Now() or a mocked version thereof.
   base::TimeTicks NowTicks() const override = 0;
 
@@ -105,7 +105,7 @@ class DOMAIN_RELIABILITY_EXPORT ActualTime : public MockableTime {
   ~ActualTime() override;
 
   // MockableTime implementation:
-  base::Time Now() override;
+  base::Time Now() const override;
   base::TimeTicks NowTicks() const override;
   std::unique_ptr<MockableTime::Timer> CreateTimer() override;
 };

components/gcm_driver/gcm_client_impl_unittest.cc

@@ -181,14 +181,14 @@ class AutoAdvancingTestClock : public base::Clock {
   explicit AutoAdvancingTestClock(base::TimeDelta auto_increment_time_delta);
   ~AutoAdvancingTestClock() override;
 
-  base::Time Now() override;
+  base::Time Now() const override;
   void Advance(TimeDelta delta);
   int call_count() const { return call_count_; }
 
  private:
-  int call_count_;
+  mutable int call_count_;
   base::TimeDelta auto_increment_time_delta_;
-  base::Time now_;
+  mutable base::Time now_;
 
   DISALLOW_COPY_AND_ASSIGN(AutoAdvancingTestClock);
 };
@@ -201,7 +201,7 @@ AutoAdvancingTestClock::AutoAdvancingTestClock(
 AutoAdvancingTestClock::~AutoAdvancingTestClock() {
 }
 
-base::Time AutoAdvancingTestClock::Now() {
+base::Time AutoAdvancingTestClock::Now() const {
   call_count_++;
   now_ += auto_increment_time_delta_;
   return now_;

net/dns/mdns_client_unittest.cc

@@ -366,7 +366,7 @@ class MockClock : public base::Clock {
   MockClock() = default;
   virtual ~MockClock() = default;
 
-  MOCK_METHOD0(Now, base::Time());
+  MOCK_CONST_METHOD0(Now, base::Time());
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockClock);